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Papers by Rupa Dey
Synthetic Communications, 2015
A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from t... more A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from their corresponding bromides. Quaternary ammonium bromides (QABs) and a N, Nʹ-heterocyclic dibromide are efficiently oxidized to their corresponding mono-tribromides and bistribromide by m-chloroperbenzoic acid (MCPBA) in presence of 2 and 4 equiv of KBr, respectively. The reactions are carried out in aq. medium without the use of any mineral acid and metal catalyst/promoters. A variety of tribromides are synthesized in very high yields including a hitherto unknown reagent viz. 1, 10-(ethane-1, 2-diyl)phenanthrolinediium bistribromide (EPDBT). EPDBT is investigated as brominating agent and found to be highly effective for selective bromination of active methylene groups of a variety of 1, 3-diketones and β-ketoesters.
Chemistry Letters, 2014
N H Br Br NH NH 2 Br − Br − (5-10°C) Magnetic Stirring (1 equiv) (Yield 95 %) NH NH Br 3 − Br 3 −... more N H Br Br NH NH 2 Br − Br − (5-10°C) Magnetic Stirring (1 equiv) (Yield 95 %) NH NH Br 3 − Br 3 − 4 equiv KBr 4 equiv H 5 IO 6 Ground, r.t. (Yield 92 %) ROH + HMDS ROSiMe 3 RSH RSSiMe 3 80-95 % 5-17 min, EDPBT (2.5 mol %) EDPBT NH 3 +
Synthetic Communications, 2014
A phosphonium-based catalyst, 2-carboxyethyltriphenyl phosphonium tribromide (CTPTB), has been sy... more A phosphonium-based catalyst, 2-carboxyethyltriphenyl phosphonium tribromide (CTPTB), has been synthesized by reacting triphenyl phosphine with acrylic acid and potassium bromide under solvent-free condition followed by oxidation of Br À to Br À 3 with KMnO 4 . This hitherto unknown tribromide reagent is characterized by ultraviolet-visible, Fourier transform-infrared, 1 H NMR, and 31 P NMR spectroscopy. Its efficacy as catalyst is established by investigating its catalytic activity in silylation of alcohols and thiols by hexamethyl disilazane (HMDS). It is found to be a very good catalyst and selectively and efficiently catalyzes the silylation reactions.
Chinese Chemical Letters, 2013
Chemistry Letters, 2014
A novel method of synthesis of organic ammonium tribromides (OATBs) is developed by using an inex... more A novel method of synthesis of organic ammonium tribromides (OATBs) is developed by using an inexpensive and eco-friendly sodium hypochlorite as oxidant for conversion of Br ¹ to Br 3 ¹ . The OATBs thus prepared include both quaternary ammonium tribromides and N-heterocyclic tribromides. A new addition to the family of OATBs is made in the form of phenanthroline hydrotribromide. The efficacy of this new tribromide as catalyst is ascertained in the oxidative transformation of organic sulfides to their corresponding sulfoxides and sulfones by hydrogen peroxide.
A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from t... more A novel procedure for the preparation of organic ammonium tribromides (OATBs)
is described from their corresponding bromides. Quaternary ammonium bromides (QABs)
and a N,N′-heterocyclic dibromide are efficiently oxidized to their corresponding
monotribromides and bistribromide by m-chloroperbenzoic acid (MCPBA) in the presence
of 2 and 4 equiv of KBr, respectively. The reactions are carried out in an aqueous medium
without the use of any mineral acid or metal catalyst/promoters. A variety of tribromides
are synthesized in very good yields including a hitherto unknown reagent, 1,10-(ethane-1,
2-diyl)phenanthrolinediium bistribromide (EPDBT). EPDBT is investigated as
brominating agent and found to be highly effective for selective bromination of active
methylene groups of a variety of 1,3-diketones and b-ketoesters.
Synthetic Communications, 2015
A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from t... more A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from their corresponding bromides. Quaternary ammonium bromides (QABs) and a N, Nʹ-heterocyclic dibromide are efficiently oxidized to their corresponding mono-tribromides and bistribromide by m-chloroperbenzoic acid (MCPBA) in presence of 2 and 4 equiv of KBr, respectively. The reactions are carried out in aq. medium without the use of any mineral acid and metal catalyst/promoters. A variety of tribromides are synthesized in very high yields including a hitherto unknown reagent viz. 1, 10-(ethane-1, 2-diyl)phenanthrolinediium bistribromide (EPDBT). EPDBT is investigated as brominating agent and found to be highly effective for selective bromination of active methylene groups of a variety of 1, 3-diketones and β-ketoesters.
Chemistry Letters, 2014
N H Br Br NH NH 2 Br − Br − (5-10°C) Magnetic Stirring (1 equiv) (Yield 95 %) NH NH Br 3 − Br 3 −... more N H Br Br NH NH 2 Br − Br − (5-10°C) Magnetic Stirring (1 equiv) (Yield 95 %) NH NH Br 3 − Br 3 − 4 equiv KBr 4 equiv H 5 IO 6 Ground, r.t. (Yield 92 %) ROH + HMDS ROSiMe 3 RSH RSSiMe 3 80-95 % 5-17 min, EDPBT (2.5 mol %) EDPBT NH 3 +
Synthetic Communications, 2014
A phosphonium-based catalyst, 2-carboxyethyltriphenyl phosphonium tribromide (CTPTB), has been sy... more A phosphonium-based catalyst, 2-carboxyethyltriphenyl phosphonium tribromide (CTPTB), has been synthesized by reacting triphenyl phosphine with acrylic acid and potassium bromide under solvent-free condition followed by oxidation of Br À to Br À 3 with KMnO 4 . This hitherto unknown tribromide reagent is characterized by ultraviolet-visible, Fourier transform-infrared, 1 H NMR, and 31 P NMR spectroscopy. Its efficacy as catalyst is established by investigating its catalytic activity in silylation of alcohols and thiols by hexamethyl disilazane (HMDS). It is found to be a very good catalyst and selectively and efficiently catalyzes the silylation reactions.
Chinese Chemical Letters, 2013
Chemistry Letters, 2014
A novel method of synthesis of organic ammonium tribromides (OATBs) is developed by using an inex... more A novel method of synthesis of organic ammonium tribromides (OATBs) is developed by using an inexpensive and eco-friendly sodium hypochlorite as oxidant for conversion of Br ¹ to Br 3 ¹ . The OATBs thus prepared include both quaternary ammonium tribromides and N-heterocyclic tribromides. A new addition to the family of OATBs is made in the form of phenanthroline hydrotribromide. The efficacy of this new tribromide as catalyst is ascertained in the oxidative transformation of organic sulfides to their corresponding sulfoxides and sulfones by hydrogen peroxide.
A novel procedure for the preparation of organic ammonium tribromides (OATBs) is described from t... more A novel procedure for the preparation of organic ammonium tribromides (OATBs)
is described from their corresponding bromides. Quaternary ammonium bromides (QABs)
and a N,N′-heterocyclic dibromide are efficiently oxidized to their corresponding
monotribromides and bistribromide by m-chloroperbenzoic acid (MCPBA) in the presence
of 2 and 4 equiv of KBr, respectively. The reactions are carried out in an aqueous medium
without the use of any mineral acid or metal catalyst/promoters. A variety of tribromides
are synthesized in very good yields including a hitherto unknown reagent, 1,10-(ethane-1,
2-diyl)phenanthrolinediium bistribromide (EPDBT). EPDBT is investigated as
brominating agent and found to be highly effective for selective bromination of active
methylene groups of a variety of 1,3-diketones and b-ketoesters.