Kevin Wellington - Academia.edu (original) (raw)
Papers by Kevin Wellington
Nuclear monoamination of a 1,4-naphthohydroquinone with primary aromatic amines was catalysed by ... more Nuclear monoamination of a 1,4-naphthohydroquinone with primary aromatic amines was catalysed by the commercial laccase, Novozym 51003, from Novozymes to afford aminonaphthoquinones. The synthesis was accomplished by reacting a mixture of the primary amine and 1,4-naphthohydroquinone in suc-cinate-lactate buffer and a co-solvent, dimethylformamide, under mild reaction conditions in a vessel open to air at pH 4.5 and pH 6.0. Anticancer screening showed that the aminonaphthoquinones exhibited potent cytostatic effects particularly against the UACC62 (melanoma) cancer cell line (GI 50 = 3.98–7.54 lM). One compound exhibited potent cytostatic effects against both the TK10 (renal) and the UACC62 (melanoma) cancer cell line. The cytostatic effects of this compound (GI 50 = 8.38 lM) against the TK10 cell line was almost as good as that of the anticancer agent, etoposide (GI 50 = 7.19 lM). Two compounds exhibited potent cyto-static effects against both the UACC62 (melanoma) and the MCF7 (breast) cancer cell lines. The total growth inhibition (TGI) of most of the compounds was better than that of etoposide against the UACC62 cell line. Three compounds (TGI = 7.17–7.94 lM) exhibited potent cytostatic effects against the UACC62 cell line which was 7 to 8-fold better than that of etoposide (TGI = 52.71 lM). The results are encouraging for further study of the aminonaphthoquinones for potential application in anticancer therapy.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright a b s t r a c t Nuclear diamination of p-hydrobenzoquinones with aromatic and aliphatic primary amines was catalysed by an immobilised commercial laccase, Denilite Ò II Base, from Novozymes. The amine and the p-hydro-benzoquinone was reacted under mild conditions (at room temperature and at 35 °C) in a reaction vessel open to air in the presence of laccase and a co-solvent to afford, exclusively, the diaminated p-benzoqui-none. These compounds may have potential antiallergic, antibiotic, anticancer, antifungal, antiviral and/ or 5-lipoxygenase inhibiting activity.
The African blue tick, Rhipicephalus (Boophilus) decoloratus, is a common tick species found in S... more The African blue tick, Rhipicephalus (Boophilus) decoloratus, is a common tick species found in South Africa and affects cattle production as well as vectoring pathogens in regions of Africa and Asia. In an attempt to develop a non-toxic, lower cost and environmentally friendly tick control method, twenty-six plant extracts were prepared from thirteen plant species using 99.5% acetone and 99% ethanol. The adapted Shaw Larval Immersion Test (SLIT) was used to test the efficacy of the extracts. A 1% solution of each of the plant extracts was prepared for efficacy testing and the ethanol extracts were found to have better acaricidal activity than the acetone extracts. The ethanol extract from the leaves and flowers of Calpurnia aurea had the best activity [corrected mortality (CM) = 82.9%] which was followed by the stem extract of Cissus quadrangularis (CM = 80.4%). The plant species were screened against Vero cells and were found to have low toxicity. From this study it is apparent that there is potential for the development of botanicals as natural acaricides against R. (B.) decoloratus.
![Research paper thumbnail of One-Pot Laccase-Catalysed Synthesis of 5,6-Dihydroxylated Benzo[b]furans and Catechol Derivatives, and Their Anticancer Activity](https://attachments.academia-assets.com/47807711/thumbnails/1.jpg)
](A commercial laccase, Suberase 1 from Novozymes, was used to catalyse the synthesis of 5,6-dihydr... more A commercial laccase, Suberase 1 from Novozymes, was used to catalyse the synthesis of 5,6-dihydroxylated benzo[b]furans and catechol derivatives. The yields were, in some cases, similar to or better than that obtained by other enzymatic, chemical or electrochemical syntheses. The synthesised derivatives were screened against renal (TK10), melanoma (UACC62), breast (MCF7) and cervical (HeLa) cancer cell lines. GI 50 , TGI and LC 50 are reported for the first time. Anticancer screening showed that the cytostatic effects of the 5,6-dihydroxylated benzo[b]furans were most effective against the melanoma (UACC62) cancer cell line with several compounds exhibiting potent growth inhibitory activities (GI 50 ¼ 0.77–9.76 mM), of which two compounds had better activity than the anticancer agent etoposide (GI 50 ¼ 0.89 mM). One compound exhibited potent activity (GI 50 ¼ 9.73 mM) against the renal (TK10) cancer cell line and two exhibited potent activity (GI 50 ¼ 8.79 and 9.30 mM) against the breast (MCF7) cancer cell line. These results encourage further studies of the 5,6-dihydroxylated benzo[b]furans for their potential application in anticancer therapy.
The non-communicable disease, cancer, is one of the major causes of death across the world and is... more The non-communicable disease, cancer, is one of the major causes of death across the world and is forecast to increase by 75% to reach close to 25 million cases over the next two decades. Radiotherapy and surgical approaches have been unsuccessful in controlling the incidence of most cancers. The development of chemotherapeutic strategies involving novel small molecule antitumour agents has therefore been the focus area of cancer chemotherapy for several decades as another strategy to combat and control the incidence of cancer. Many natural products as well as several synthetic drugs have a naphthoquinone chromophore. The anticancer activities of naphthoquinones have been the focus of much research to discover novel anticancer agents. The naturally occurring 1,2-naphthoquinone-based compound, b-lapachone (ARQ 761), is currently being assessed for its anti-tumour activity against advanced solid tumours. This review describes the most recent applications of naphthoquinones and their derivatives in cancer drug discovery. The biology relevant to the design of novel naphthoquinone anticancer agents is also discussed. Furthermore, the discussion of the biology will contribute to understanding cancer as well as the applications of naphthoquinones as anticancer agents.
In this article, we focus on the synthesis of aryl C-glycosides via Heck coupling. It is organize... more In this article, we focus on the synthesis of aryl C-glycosides via Heck coupling. It is organized based on the type of structures used in the assembly of the C-glycosides (also called C-nucleosides) with the following subsections: pyrimidine C-nucleosides, purine C-nucleosides, and monocyclic, bicyclic, and tetracyclic C-nucleosides. The reagents and conditions used for conducting the Heck coupling reactions are discussed. The subsequent conversion of the Heck products to the corresponding target molecules and the application of the target molecules are also described.
RSC Adv., 2015
The non-communicable disease, cancer, is one of the major causes of death across the world and is... more The non-communicable disease, cancer, is one of the major causes of death across the world and is forecast to increase by 75% to reach close to 25 million cases over the next two decades. Radiotherapy and surgical approaches have been unsuccessful in controlling the incidence of most cancers. The development of chemotherapeutic strategies involving novel small molecule antitumour agents has therefore been the focus area of cancer chemotherapy for several decades as another strategy to combat and control the incidence of cancer. Many natural products as well as several synthetic drugs have a naphthoquinone chromophore. The anticancer activities of naphthoquinones have been the focus of much research to discover novel anticancer agents. The naturally occurring 1,2naphthoquinone-based compound, b-lapachone (ARQ 761), is currently being assessed for its antitumour activity against advanced solid tumours. This review describes the most recent applications of naphthoquinones and their derivatives in cancer drug discovery. The biology relevant to the design of novel naphthoquinone anticancer agents is also discussed. Furthermore, the discussion of the biology will contribute to understanding cancer as well as the applications of naphthoquinones as anticancer agents.
Laccases are oxidoreductases that are part of the family of multinuclear copper-containing oxidas... more Laccases are oxidoreductases that are part of the family of multinuclear copper-containing oxidases. A feature of these enzymes is that they catalyze the monoelectronic oxidation of substrates using molecular oxygen and release water as the only by-product. Laccase substrates are typically phenols and amines, and the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. The search for new, efficient and environmentally benign processes for the textile and pulp and paper industries has increased interest in these ‘green’ catalysts. At present the application of laccases range from the textile to the pulp and paper industries and from food applications to bioremediation processes. In recent years interest in the application of laccases in organic synthesis has grown with the development of Green Chemistry. This review provides an overview of the developments in the applications of laccases in primarily the field of organic synthesis. O...
ChemInform, 2012
A One-Pot Synthesis of 1,4-Naphthoquinone-2,3-bis-sulfides Catalyzed by a Commercial Laccase. -An... more A One-Pot Synthesis of 1,4-Naphthoquinone-2,3-bis-sulfides Catalyzed by a Commercial Laccase. -An oxidative C-S bond formation with alkyl and aryl thiols (II) and (IV) is achieved under mild conditions from both the naphthohydroquinone carboxylic acid (I) and the naphthohydroquinone (VI), enabling direct access to naphthoquinone (bis)sulfides such as and (V). The one-pot laccase methodology requires no chemical oxidant, avoids a chlorinated intermediate, as well as the need for activation of alkyl thiols with sodium. The product formation depends on factors like the pH-value of the reaction mixture, the solubility of the substrates, nucleophilicity, and the amounts of thiols used. -(WELLINGTON*, K. W.; BOKAKO, R.; RASEROKA, N.; STEENKAMP, P.; Green Chem. 14 (2012) 9, 2567-2576, http://dx.doi.org/10.1039/c2gc35926j ; CSIR Biosci., Pretoria 0001, S. Afr.; Eng.) -H. Hoennerscheid 51-094
Bioorganic & Medicinal Chemistry
a b s t r a c t Nuclear diamination of p-hydrobenzoquinones with aromatic and aliphatic primary a... more a b s t r a c t Nuclear diamination of p-hydrobenzoquinones with aromatic and aliphatic primary amines was catalysed by an immobilised commercial laccase, Denilite Ò II Base, from Novozymes. The amine and the p-hydro-benzoquinone was reacted under mild conditions (at room temperature and at 35 °C) in a reaction vessel open to air in the presence of laccase and a co-solvent to afford, exclusively, the diaminated p-benzoqui-none. These compounds may have potential antiallergic, antibiotic, anticancer, antifungal, antiviral and/ or 5-lipoxygenase inhibiting activity.
ARKIVOC: archive for organic chemistry
A series of Co(II) and Cu(II) complexes have been prepared, and their structures investigated usi... more A series of Co(II) and Cu(II) complexes have been prepared, and their structures investigated using a combination of microanalytical, spectroscopic, electrochemical and X-ray crystallographic techniques. The capacity of the complexes to oxidise phenol and catechol substrates has been examined, and while some of the Cu(II) complexes catalyse oxidative coupling of 2,4-di-t-butylphenol (DTBP) to the corresponding biphenyl (9–13%), the Co(II) complexes catalyse efficient conversion (up to 92%) of 3,5-di-t-butylcatechol (DTBC) to the o-quinone within 24 h.
ChemCatChem
Oxidative C-S and C-C bond formation with aryl and alkyl thiols was catalysed under mild conditio... more Oxidative C-S and C-C bond formation with aryl and alkyl thiols was catalysed under mild conditions in a reaction vessel open to air at pH 4.5 in the presence of a commercial laccase (Novozym 51003 or Suberase) and a co-solvent (DMF) to afford 1,4-naphthoquinone sulfides. Both monothiolation and dithiolation of the 1,4-naphthohydroquinone was accomplished with the latter being favoured. In addition, unprecedented dimerisation of monothiolated intermediates occurred via C-C coupling. These commercial laccases provide a facile and a more environmentally friendly synthetic approach to both the 1,4-naphthoquinone sulfides and the 1,4-naphthoquinone sulfide dimers.
Copper(I), copper(II), cobalt(II) and zinc(II) complexes of amacrocyclic,multidentate Schiff-base... more Copper(I), copper(II), cobalt(II) and zinc(II) complexes of amacrocyclic,multidentate Schiff-base ligand have been prepared and, with the exception of the zinc(II) complex, have been shown to exhibit biomimetic catecholase activity.
Tetrahedron Letters, 2004
Sulfonamides have been identified as by-products in the base-mediated transesterification of N-un... more Sulfonamides have been identified as by-products in the base-mediated transesterification of N-unsubstituted carbamates with sulfonyl chlorides to give the corresponding sulfonates. A proposed mechanism and the synthesis of hindered 2,6-disubstituted arylsulfonates via this method are also reported.
Synthetic Communications, 2000
Synthetic Communications, 2001
Synthetic Communications, 2001
Nucleosides, Nucleotides and Nucleic Acids, 2009
2 The syntheses of N,N -dibenzyl-2,4-diaminopyrimidine-2 -deoxyribonucleoside and 1-methyl-2deoxy... more 2 The syntheses of N,N -dibenzyl-2,4-diaminopyrimidine-2 -deoxyribonucleoside and 1-methyl-2deoxypseudoisocytidine via Heck coupling are described. A survey of the attempts to use the Heck coupling to synthesize N,N -dibenzyl-2,4-diaminopyrimidine-2 -deoxyribonucleoside is provided, indicating a remarkable diversity in outcome depending on the specific heterocyclic partner used.
Nuclear monoamination of a 1,4-naphthohydroquinone with primary aromatic amines was catalysed by ... more Nuclear monoamination of a 1,4-naphthohydroquinone with primary aromatic amines was catalysed by the commercial laccase, Novozym 51003, from Novozymes to afford aminonaphthoquinones. The synthesis was accomplished by reacting a mixture of the primary amine and 1,4-naphthohydroquinone in suc-cinate-lactate buffer and a co-solvent, dimethylformamide, under mild reaction conditions in a vessel open to air at pH 4.5 and pH 6.0. Anticancer screening showed that the aminonaphthoquinones exhibited potent cytostatic effects particularly against the UACC62 (melanoma) cancer cell line (GI 50 = 3.98–7.54 lM). One compound exhibited potent cytostatic effects against both the TK10 (renal) and the UACC62 (melanoma) cancer cell line. The cytostatic effects of this compound (GI 50 = 8.38 lM) against the TK10 cell line was almost as good as that of the anticancer agent, etoposide (GI 50 = 7.19 lM). Two compounds exhibited potent cyto-static effects against both the UACC62 (melanoma) and the MCF7 (breast) cancer cell lines. The total growth inhibition (TGI) of most of the compounds was better than that of etoposide against the UACC62 cell line. Three compounds (TGI = 7.17–7.94 lM) exhibited potent cytostatic effects against the UACC62 cell line which was 7 to 8-fold better than that of etoposide (TGI = 52.71 lM). The results are encouraging for further study of the aminonaphthoquinones for potential application in anticancer therapy.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright a b s t r a c t Nuclear diamination of p-hydrobenzoquinones with aromatic and aliphatic primary amines was catalysed by an immobilised commercial laccase, Denilite Ò II Base, from Novozymes. The amine and the p-hydro-benzoquinone was reacted under mild conditions (at room temperature and at 35 °C) in a reaction vessel open to air in the presence of laccase and a co-solvent to afford, exclusively, the diaminated p-benzoqui-none. These compounds may have potential antiallergic, antibiotic, anticancer, antifungal, antiviral and/ or 5-lipoxygenase inhibiting activity.
The African blue tick, Rhipicephalus (Boophilus) decoloratus, is a common tick species found in S... more The African blue tick, Rhipicephalus (Boophilus) decoloratus, is a common tick species found in South Africa and affects cattle production as well as vectoring pathogens in regions of Africa and Asia. In an attempt to develop a non-toxic, lower cost and environmentally friendly tick control method, twenty-six plant extracts were prepared from thirteen plant species using 99.5% acetone and 99% ethanol. The adapted Shaw Larval Immersion Test (SLIT) was used to test the efficacy of the extracts. A 1% solution of each of the plant extracts was prepared for efficacy testing and the ethanol extracts were found to have better acaricidal activity than the acetone extracts. The ethanol extract from the leaves and flowers of Calpurnia aurea had the best activity [corrected mortality (CM) = 82.9%] which was followed by the stem extract of Cissus quadrangularis (CM = 80.4%). The plant species were screened against Vero cells and were found to have low toxicity. From this study it is apparent that there is potential for the development of botanicals as natural acaricides against R. (B.) decoloratus.
A commercial laccase, Suberase 1 from Novozymes, was used to catalyse the synthesis of 5,6-dihydr... more A commercial laccase, Suberase 1 from Novozymes, was used to catalyse the synthesis of 5,6-dihydroxylated benzo[b]furans and catechol derivatives. The yields were, in some cases, similar to or better than that obtained by other enzymatic, chemical or electrochemical syntheses. The synthesised derivatives were screened against renal (TK10), melanoma (UACC62), breast (MCF7) and cervical (HeLa) cancer cell lines. GI 50 , TGI and LC 50 are reported for the first time. Anticancer screening showed that the cytostatic effects of the 5,6-dihydroxylated benzo[b]furans were most effective against the melanoma (UACC62) cancer cell line with several compounds exhibiting potent growth inhibitory activities (GI 50 ¼ 0.77–9.76 mM), of which two compounds had better activity than the anticancer agent etoposide (GI 50 ¼ 0.89 mM). One compound exhibited potent activity (GI 50 ¼ 9.73 mM) against the renal (TK10) cancer cell line and two exhibited potent activity (GI 50 ¼ 8.79 and 9.30 mM) against the breast (MCF7) cancer cell line. These results encourage further studies of the 5,6-dihydroxylated benzo[b]furans for their potential application in anticancer therapy.
The non-communicable disease, cancer, is one of the major causes of death across the world and is... more The non-communicable disease, cancer, is one of the major causes of death across the world and is forecast to increase by 75% to reach close to 25 million cases over the next two decades. Radiotherapy and surgical approaches have been unsuccessful in controlling the incidence of most cancers. The development of chemotherapeutic strategies involving novel small molecule antitumour agents has therefore been the focus area of cancer chemotherapy for several decades as another strategy to combat and control the incidence of cancer. Many natural products as well as several synthetic drugs have a naphthoquinone chromophore. The anticancer activities of naphthoquinones have been the focus of much research to discover novel anticancer agents. The naturally occurring 1,2-naphthoquinone-based compound, b-lapachone (ARQ 761), is currently being assessed for its anti-tumour activity against advanced solid tumours. This review describes the most recent applications of naphthoquinones and their derivatives in cancer drug discovery. The biology relevant to the design of novel naphthoquinone anticancer agents is also discussed. Furthermore, the discussion of the biology will contribute to understanding cancer as well as the applications of naphthoquinones as anticancer agents.
In this article, we focus on the synthesis of aryl C-glycosides via Heck coupling. It is organize... more In this article, we focus on the synthesis of aryl C-glycosides via Heck coupling. It is organized based on the type of structures used in the assembly of the C-glycosides (also called C-nucleosides) with the following subsections: pyrimidine C-nucleosides, purine C-nucleosides, and monocyclic, bicyclic, and tetracyclic C-nucleosides. The reagents and conditions used for conducting the Heck coupling reactions are discussed. The subsequent conversion of the Heck products to the corresponding target molecules and the application of the target molecules are also described.
RSC Adv., 2015
The non-communicable disease, cancer, is one of the major causes of death across the world and is... more The non-communicable disease, cancer, is one of the major causes of death across the world and is forecast to increase by 75% to reach close to 25 million cases over the next two decades. Radiotherapy and surgical approaches have been unsuccessful in controlling the incidence of most cancers. The development of chemotherapeutic strategies involving novel small molecule antitumour agents has therefore been the focus area of cancer chemotherapy for several decades as another strategy to combat and control the incidence of cancer. Many natural products as well as several synthetic drugs have a naphthoquinone chromophore. The anticancer activities of naphthoquinones have been the focus of much research to discover novel anticancer agents. The naturally occurring 1,2naphthoquinone-based compound, b-lapachone (ARQ 761), is currently being assessed for its antitumour activity against advanced solid tumours. This review describes the most recent applications of naphthoquinones and their derivatives in cancer drug discovery. The biology relevant to the design of novel naphthoquinone anticancer agents is also discussed. Furthermore, the discussion of the biology will contribute to understanding cancer as well as the applications of naphthoquinones as anticancer agents.
Laccases are oxidoreductases that are part of the family of multinuclear copper-containing oxidas... more Laccases are oxidoreductases that are part of the family of multinuclear copper-containing oxidases. A feature of these enzymes is that they catalyze the monoelectronic oxidation of substrates using molecular oxygen and release water as the only by-product. Laccase substrates are typically phenols and amines, and the reaction products are dimers and oligomers derived from the coupling of reactive radical intermediates. The search for new, efficient and environmentally benign processes for the textile and pulp and paper industries has increased interest in these ‘green’ catalysts. At present the application of laccases range from the textile to the pulp and paper industries and from food applications to bioremediation processes. In recent years interest in the application of laccases in organic synthesis has grown with the development of Green Chemistry. This review provides an overview of the developments in the applications of laccases in primarily the field of organic synthesis. O...
ChemInform, 2012
A One-Pot Synthesis of 1,4-Naphthoquinone-2,3-bis-sulfides Catalyzed by a Commercial Laccase. -An... more A One-Pot Synthesis of 1,4-Naphthoquinone-2,3-bis-sulfides Catalyzed by a Commercial Laccase. -An oxidative C-S bond formation with alkyl and aryl thiols (II) and (IV) is achieved under mild conditions from both the naphthohydroquinone carboxylic acid (I) and the naphthohydroquinone (VI), enabling direct access to naphthoquinone (bis)sulfides such as and (V). The one-pot laccase methodology requires no chemical oxidant, avoids a chlorinated intermediate, as well as the need for activation of alkyl thiols with sodium. The product formation depends on factors like the pH-value of the reaction mixture, the solubility of the substrates, nucleophilicity, and the amounts of thiols used. -(WELLINGTON*, K. W.; BOKAKO, R.; RASEROKA, N.; STEENKAMP, P.; Green Chem. 14 (2012) 9, 2567-2576, http://dx.doi.org/10.1039/c2gc35926j ; CSIR Biosci., Pretoria 0001, S. Afr.; Eng.) -H. Hoennerscheid 51-094
Bioorganic & Medicinal Chemistry
a b s t r a c t Nuclear diamination of p-hydrobenzoquinones with aromatic and aliphatic primary a... more a b s t r a c t Nuclear diamination of p-hydrobenzoquinones with aromatic and aliphatic primary amines was catalysed by an immobilised commercial laccase, Denilite Ò II Base, from Novozymes. The amine and the p-hydro-benzoquinone was reacted under mild conditions (at room temperature and at 35 °C) in a reaction vessel open to air in the presence of laccase and a co-solvent to afford, exclusively, the diaminated p-benzoqui-none. These compounds may have potential antiallergic, antibiotic, anticancer, antifungal, antiviral and/ or 5-lipoxygenase inhibiting activity.
ARKIVOC: archive for organic chemistry
A series of Co(II) and Cu(II) complexes have been prepared, and their structures investigated usi... more A series of Co(II) and Cu(II) complexes have been prepared, and their structures investigated using a combination of microanalytical, spectroscopic, electrochemical and X-ray crystallographic techniques. The capacity of the complexes to oxidise phenol and catechol substrates has been examined, and while some of the Cu(II) complexes catalyse oxidative coupling of 2,4-di-t-butylphenol (DTBP) to the corresponding biphenyl (9–13%), the Co(II) complexes catalyse efficient conversion (up to 92%) of 3,5-di-t-butylcatechol (DTBC) to the o-quinone within 24 h.
ChemCatChem
Oxidative C-S and C-C bond formation with aryl and alkyl thiols was catalysed under mild conditio... more Oxidative C-S and C-C bond formation with aryl and alkyl thiols was catalysed under mild conditions in a reaction vessel open to air at pH 4.5 in the presence of a commercial laccase (Novozym 51003 or Suberase) and a co-solvent (DMF) to afford 1,4-naphthoquinone sulfides. Both monothiolation and dithiolation of the 1,4-naphthohydroquinone was accomplished with the latter being favoured. In addition, unprecedented dimerisation of monothiolated intermediates occurred via C-C coupling. These commercial laccases provide a facile and a more environmentally friendly synthetic approach to both the 1,4-naphthoquinone sulfides and the 1,4-naphthoquinone sulfide dimers.
Copper(I), copper(II), cobalt(II) and zinc(II) complexes of amacrocyclic,multidentate Schiff-base... more Copper(I), copper(II), cobalt(II) and zinc(II) complexes of amacrocyclic,multidentate Schiff-base ligand have been prepared and, with the exception of the zinc(II) complex, have been shown to exhibit biomimetic catecholase activity.
Tetrahedron Letters, 2004
Sulfonamides have been identified as by-products in the base-mediated transesterification of N-un... more Sulfonamides have been identified as by-products in the base-mediated transesterification of N-unsubstituted carbamates with sulfonyl chlorides to give the corresponding sulfonates. A proposed mechanism and the synthesis of hindered 2,6-disubstituted arylsulfonates via this method are also reported.
Synthetic Communications, 2000
Synthetic Communications, 2001
Synthetic Communications, 2001
Nucleosides, Nucleotides and Nucleic Acids, 2009
2 The syntheses of N,N -dibenzyl-2,4-diaminopyrimidine-2 -deoxyribonucleoside and 1-methyl-2deoxy... more 2 The syntheses of N,N -dibenzyl-2,4-diaminopyrimidine-2 -deoxyribonucleoside and 1-methyl-2deoxypseudoisocytidine via Heck coupling are described. A survey of the attempts to use the Heck coupling to synthesize N,N -dibenzyl-2,4-diaminopyrimidine-2 -deoxyribonucleoside is provided, indicating a remarkable diversity in outcome depending on the specific heterocyclic partner used.