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Research paper thumbnail of CCDC 988194: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 927617: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 937011: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Iron(III)-Catalyzed Regioselective Synthesis of Electron-Rich Benzothiazoles from Aryl Isothiocyanates via CH Functionalization

Research paper thumbnail of Iodobenzene Catalyzed C–H Amination of <i>N</i>‑Substituted Amidines Using <i>m</i>‑Chloroperbenzoic Acid

The oxidative C–H amination of <i>N</i>″-aryl-<i>N</i>′-tosyl/<i>N&... more The oxidative C–H amination of <i>N</i>″-aryl-<i>N</i>′-tosyl/<i>N</i>′-methylsulfonylamidines and <i>N,N</i>′-bis(aryl)amidines has been accomplished using iodobenzene as a catalyst to furnish 1,2-disubstituted benzimidazoles in the presence of <i>m</i>CPBA as a terminal oxidant at room temperature. The reaction is general, and the target products can be obtained in moderate to high yields

Research paper thumbnail of Studies Toward Metal-Free Synthesis of Benzofuzed Azoles Using Hypervalent Iodine

The research work presented in this thesis has been divided into five chapters. The first chapter... more The research work presented in this thesis has been divided into five chapters. The first chapter focuses on the recent developments in hypervalent iodine chemistry. The second chapter describes iodobenzene catalyzed synthesis of substituted benzimidazoles using mCPBA as a terminal oxidant. The third and fourth chapters present the synthesis of substituted benzoxazoles and benzothiazoles using 1-iodo-4-nitrobenzene in the presence of oxone as an oxidant. The last chapter deals with the oxidative C-N bond formation of N,N'-diarylureas for the synthesis of substituted benzimidazol-2-ones using phenyliodine bis(trifluoroacetate). Chapter 1. Recent Developments in Hypervalent Iodine Chemistry Hypervalent compounds are those containing a main group element (Group V-VIII) with more than an octet of electrons in its valence shell. The bonding in hypervalent compounds was explained by three-center-four-electron (3c-4e) bond and they are named according to Martin-Arduengo designation. Hypervalent iodine compounds owing to their mild and selective oxidizing properties are used to a great extent in synthetic organic chemistry for the construction of carbon-carbon and carbon-heteroatom bonds. In recent years, many research groups have focused on the catalytic utilization of these reagents by developing new catalytic processes where the iodine(III) species was generated in situ using catalytic amount of iodoarenes and a stoichiometric oxidant. Chapter 2. Iodobenzene Catalyzed C-H Amination of N-Substituted Amidines Using m-Chloroperbenzoic Acid Benzimidazoles are an important class of heterocyclic compounds found in a wide variety of medicinally important molecules. This chapter presents iodobenzene catalyzed synthesis of substituted benzimidazoles from N,N′-bis(aryl)amidines and N 1-Phenyl-N 2-(4-methylbenze-ne/methylsulfonyl)amidines via oxidative C-H amination in the presence of mCPBA as a terminal oxidant at room temperature in HFIP as solvent (Scheme 1). TH-1478_10612205 viii Scheme 1. Synthesis of Substituted Benzimidazoles Chapter 3. Iodobenzene Catalyzed Synthesis of Benzoxazoles Using Oxone via CO Bond Formation Benzoxazoles constitute a prominent class of heterocycles possessing important medicinal properties and are a privileged structural units in a diverse range of natural products and synthetic drugs with wide applications. This chapter describes a metal-free, 1-iodo-4nitrobenzene catalyzed synthesis of 2-arylbenzoxazoles from anilides in the presence of environmentally benign oxone as a terminal oxidant at room temperature. The reaction proceeds via an oxidative C-H functionalization/C-O bond formation providing the desired products in good yields. This protocol can readily be extended for the construction of 2-alkylbenzoxazoles (Scheme 2). Scheme 2. Synthesis of Substituted Benzoxazoles Chapter 4. Iodobenzene Catalyzed Synthesis of Benzothiazoles Using Oxone via C-S Bond Formation The construction of benzothiazole structural motifs have been a topic of immense interest in recent years due to their presence in a number of natural products and biologically active compounds and they are used as drugs for several diseases such as tumors, diabetes and inflammatory diseases. The present method uses 1-iodo-4-nitrobenzene as catalyst to synthesize substituted benzothiazoles from aryl/alkylthioanilides in the presence of environmentally benign oxone as a terminal oxidant at room temperature. The scope of TH-1478_10612205 ix the reaction was carried out with different aryl/alkylthioanilides derived from corresponding anilides to give desired products in good yields (Scheme 3). Scheme 3. Synthesis of Substituted Benzothiazoles Chapter 5. Hypervalent Iodine Mediated Synthesis of Benzimidazol-2-ones Benzimidazol-2-ones are found in a wide variety of natural products and have attracted considerable interest due to their wide spectrum of biological activity. A metal-free synthesis of substituted benzimidazol-2-ones from N,N'-diarylureas using PhI(OCOCF 3) 2 at room temperature in TFE as solvent has been described in this chapter (Scheme 4).

Research paper thumbnail of Retraction of "Room-Temperature Cu(II)-Catalyzed Chemo- and Regioselective Ortho-Nitration of Arenes via C-H Functionalization

The Journal of organic chemistry, Jan 20, 2015

Research paper thumbnail of ChemInform Abstract: Room-Temperature Cu(II)-Catalyzed Chemo- and Regioselective ortho-Nitration of Arenes via C-H Functionalization

ChemInform, 2015

An efficient Cu-catalyzed chemo- and regioselective ortho-nitration of N,1-diaryl-5-aminotetrazol... more An efficient Cu-catalyzed chemo- and regioselective ortho-nitration of N,1-diaryl-5-aminotetrazoles and N,4-diaryl-3-amino-1,2,4-triazoles have been described with good functional group compatibility. The procedure features the use of operationally simple protocol utilizing the commercially available less toxic CuCl2·2H2O as catalyst and Fe(NO3)3·9H2O as nitration source at room temperature. Removal of the 5-aminotetrazole directing group has been demonstrated using base hydrolysis to afford substituted 2-nitroanilines.

Research paper thumbnail of Pd(II)-Catalyzed Aminotetrazole-Directed Ortho-Selective Halogenation of Arenes

The Journal of Organic Chemistry, 2013

A Pd(II)-catalyzed ortho-selective halogenation of N-aryl ring of N,1-diaryl-1H-tetrazol-5-amine ... more A Pd(II)-catalyzed ortho-selective halogenation of N-aryl ring of N,1-diaryl-1H-tetrazol-5-amine has been described employing N-halosuccinimide as a halogen source via C-H bond activation. The present work features 5-aminotetrazole, as a directing group, for the chemo- and regioselective C-H halogenation of arenes. The kinetic isotope study (kH/kD = 2.9) suggests that the cleavage of the C-H bond takes place in the rate-determining step. The scope and mechanism of the protocol have been demonstrated.

Research paper thumbnail of Iodobenzene Catalyzed C–H Amination of N -Substituted Amidines Using m -Chloroperbenzoic Acid

Organic Letters, 2013

The oxidative C-H amination of N&amp;amp;amp;amp;amp;amp;amp;amp;quot;-aryl-N&amp;amp;amp... more The oxidative C-H amination of N&amp;amp;amp;amp;amp;amp;amp;amp;quot;-aryl-N&amp;amp;amp;amp;amp;amp;amp;amp;#39;-tosyl/N&amp;amp;amp;amp;amp;amp;amp;amp;#39;-methylsulfonylamidines and N,N&amp;amp;amp;amp;amp;amp;amp;amp;#39;-bis(aryl)amidines has been accomplished using iodobenzene as a catalyst to furnish 1,2-disubstituted benzimidazoles in the presence of mCPBA as a terminal oxidant at room temperature. The reaction is general, and the target products can be obtained in moderate to high yields.

Research paper thumbnail of Organocatalytic Syntheses of Benzoxazoles and Benzothiazoles using Aryl Iodide and Oxone via C–H Functionalization and C–O/S Bond Formation

The Journal of Organic Chemistry, 2014

An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is... more An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C-H functionalization and C-O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.

Research paper thumbnail of CCDC 988194: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 927617: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 937011: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Iron(III)-Catalyzed Regioselective Synthesis of Electron-Rich Benzothiazoles from Aryl Isothiocyanates via CH Functionalization

Research paper thumbnail of Iodobenzene Catalyzed C–H Amination of <i>N</i>‑Substituted Amidines Using <i>m</i>‑Chloroperbenzoic Acid

The oxidative C–H amination of <i>N</i>″-aryl-<i>N</i>′-tosyl/<i>N&... more The oxidative C–H amination of <i>N</i>″-aryl-<i>N</i>′-tosyl/<i>N</i>′-methylsulfonylamidines and <i>N,N</i>′-bis(aryl)amidines has been accomplished using iodobenzene as a catalyst to furnish 1,2-disubstituted benzimidazoles in the presence of <i>m</i>CPBA as a terminal oxidant at room temperature. The reaction is general, and the target products can be obtained in moderate to high yields

Research paper thumbnail of Studies Toward Metal-Free Synthesis of Benzofuzed Azoles Using Hypervalent Iodine

The research work presented in this thesis has been divided into five chapters. The first chapter... more The research work presented in this thesis has been divided into five chapters. The first chapter focuses on the recent developments in hypervalent iodine chemistry. The second chapter describes iodobenzene catalyzed synthesis of substituted benzimidazoles using mCPBA as a terminal oxidant. The third and fourth chapters present the synthesis of substituted benzoxazoles and benzothiazoles using 1-iodo-4-nitrobenzene in the presence of oxone as an oxidant. The last chapter deals with the oxidative C-N bond formation of N,N'-diarylureas for the synthesis of substituted benzimidazol-2-ones using phenyliodine bis(trifluoroacetate). Chapter 1. Recent Developments in Hypervalent Iodine Chemistry Hypervalent compounds are those containing a main group element (Group V-VIII) with more than an octet of electrons in its valence shell. The bonding in hypervalent compounds was explained by three-center-four-electron (3c-4e) bond and they are named according to Martin-Arduengo designation. Hypervalent iodine compounds owing to their mild and selective oxidizing properties are used to a great extent in synthetic organic chemistry for the construction of carbon-carbon and carbon-heteroatom bonds. In recent years, many research groups have focused on the catalytic utilization of these reagents by developing new catalytic processes where the iodine(III) species was generated in situ using catalytic amount of iodoarenes and a stoichiometric oxidant. Chapter 2. Iodobenzene Catalyzed C-H Amination of N-Substituted Amidines Using m-Chloroperbenzoic Acid Benzimidazoles are an important class of heterocyclic compounds found in a wide variety of medicinally important molecules. This chapter presents iodobenzene catalyzed synthesis of substituted benzimidazoles from N,N′-bis(aryl)amidines and N 1-Phenyl-N 2-(4-methylbenze-ne/methylsulfonyl)amidines via oxidative C-H amination in the presence of mCPBA as a terminal oxidant at room temperature in HFIP as solvent (Scheme 1). TH-1478_10612205 viii Scheme 1. Synthesis of Substituted Benzimidazoles Chapter 3. Iodobenzene Catalyzed Synthesis of Benzoxazoles Using Oxone via CO Bond Formation Benzoxazoles constitute a prominent class of heterocycles possessing important medicinal properties and are a privileged structural units in a diverse range of natural products and synthetic drugs with wide applications. This chapter describes a metal-free, 1-iodo-4nitrobenzene catalyzed synthesis of 2-arylbenzoxazoles from anilides in the presence of environmentally benign oxone as a terminal oxidant at room temperature. The reaction proceeds via an oxidative C-H functionalization/C-O bond formation providing the desired products in good yields. This protocol can readily be extended for the construction of 2-alkylbenzoxazoles (Scheme 2). Scheme 2. Synthesis of Substituted Benzoxazoles Chapter 4. Iodobenzene Catalyzed Synthesis of Benzothiazoles Using Oxone via C-S Bond Formation The construction of benzothiazole structural motifs have been a topic of immense interest in recent years due to their presence in a number of natural products and biologically active compounds and they are used as drugs for several diseases such as tumors, diabetes and inflammatory diseases. The present method uses 1-iodo-4-nitrobenzene as catalyst to synthesize substituted benzothiazoles from aryl/alkylthioanilides in the presence of environmentally benign oxone as a terminal oxidant at room temperature. The scope of TH-1478_10612205 ix the reaction was carried out with different aryl/alkylthioanilides derived from corresponding anilides to give desired products in good yields (Scheme 3). Scheme 3. Synthesis of Substituted Benzothiazoles Chapter 5. Hypervalent Iodine Mediated Synthesis of Benzimidazol-2-ones Benzimidazol-2-ones are found in a wide variety of natural products and have attracted considerable interest due to their wide spectrum of biological activity. A metal-free synthesis of substituted benzimidazol-2-ones from N,N'-diarylureas using PhI(OCOCF 3) 2 at room temperature in TFE as solvent has been described in this chapter (Scheme 4).

Research paper thumbnail of Retraction of "Room-Temperature Cu(II)-Catalyzed Chemo- and Regioselective Ortho-Nitration of Arenes via C-H Functionalization

The Journal of organic chemistry, Jan 20, 2015

Research paper thumbnail of ChemInform Abstract: Room-Temperature Cu(II)-Catalyzed Chemo- and Regioselective ortho-Nitration of Arenes via C-H Functionalization

ChemInform, 2015

An efficient Cu-catalyzed chemo- and regioselective ortho-nitration of N,1-diaryl-5-aminotetrazol... more An efficient Cu-catalyzed chemo- and regioselective ortho-nitration of N,1-diaryl-5-aminotetrazoles and N,4-diaryl-3-amino-1,2,4-triazoles have been described with good functional group compatibility. The procedure features the use of operationally simple protocol utilizing the commercially available less toxic CuCl2·2H2O as catalyst and Fe(NO3)3·9H2O as nitration source at room temperature. Removal of the 5-aminotetrazole directing group has been demonstrated using base hydrolysis to afford substituted 2-nitroanilines.

Research paper thumbnail of Pd(II)-Catalyzed Aminotetrazole-Directed Ortho-Selective Halogenation of Arenes

The Journal of Organic Chemistry, 2013

A Pd(II)-catalyzed ortho-selective halogenation of N-aryl ring of N,1-diaryl-1H-tetrazol-5-amine ... more A Pd(II)-catalyzed ortho-selective halogenation of N-aryl ring of N,1-diaryl-1H-tetrazol-5-amine has been described employing N-halosuccinimide as a halogen source via C-H bond activation. The present work features 5-aminotetrazole, as a directing group, for the chemo- and regioselective C-H halogenation of arenes. The kinetic isotope study (kH/kD = 2.9) suggests that the cleavage of the C-H bond takes place in the rate-determining step. The scope and mechanism of the protocol have been demonstrated.

Research paper thumbnail of Iodobenzene Catalyzed C–H Amination of N -Substituted Amidines Using m -Chloroperbenzoic Acid

Organic Letters, 2013

The oxidative C-H amination of N&amp;amp;amp;amp;amp;amp;amp;amp;quot;-aryl-N&amp;amp;amp... more The oxidative C-H amination of N&amp;amp;amp;amp;amp;amp;amp;amp;quot;-aryl-N&amp;amp;amp;amp;amp;amp;amp;amp;#39;-tosyl/N&amp;amp;amp;amp;amp;amp;amp;amp;#39;-methylsulfonylamidines and N,N&amp;amp;amp;amp;amp;amp;amp;amp;#39;-bis(aryl)amidines has been accomplished using iodobenzene as a catalyst to furnish 1,2-disubstituted benzimidazoles in the presence of mCPBA as a terminal oxidant at room temperature. The reaction is general, and the target products can be obtained in moderate to high yields.

Research paper thumbnail of Organocatalytic Syntheses of Benzoxazoles and Benzothiazoles using Aryl Iodide and Oxone via C–H Functionalization and C–O/S Bond Formation

The Journal of Organic Chemistry, 2014

An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is... more An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C-H functionalization and C-O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.