Zinc(II) Perchlorate Hexahydrate Catalyzed Opening of Epoxide Ring by Amines: Applications to Synthesis of (<i>RS</i>)/(<i>R</i>)-Propranolols and (<i>RS</i>)/(<i>R</i>)/(<i>S</i>)-Naftopidils
作者:Shivani、Brahmam Pujala、Asit K. Chakraborti
DOI:10.1021/jo062674j
日期:2007.5.1
perchlorate hexahydrate was found to be the best catalyst compared to other metal perchlorates. The counteranion modulated the catalytic property of the various Zn(II) compounds that followed the order Zn(ClO4)2·6H2O ≫ Zn(BF4)2 ∼ Zn(OTf)2 ≫ ZnI2 > ZnBr2 > ZnCl2 > Zn(OAc)2 > Zn(CO3)2 in parallelism with the acidic strength of the corresponding protic acids (except for TfOH). The applicability of the methodology
Zinc Tetrafluoroborate Hydrate as a Mild Catalyst for Epoxide Ring Opening with Amines: Scope and Limitations of Metal Tetrafluoroborates and Applications in the Synthesis of Antihypertensive Drugs (<i>RS</i>)/(<i>R</i>)/(<i>S</i>)-Metoprolols
作者:Brahmam Pujala、Shivani Rana、Asit K. Chakraborti
DOI:10.1021/jo201473f
日期:2011.11.4
reaction at the benzylic carbon of the epoxide ring. A reversal of regioselectivity (91:1–69:31) in favor of the reaction at the terminal carbon of the epoxide ring was observed for reaction with morpholine. The regioselectivity was dependent on the electronic and steric factors of the epoxide and the pKa of the amine and independent of amine nucleophilicity. The role of the metal tetrafluoroborates is
已经研究了金属四氟硼酸盐与胺进行环氧化物开环反应的范围和局限性,并且发现Zn(BF 4)2 · x H 2 O是一种温和而有效的催化剂,在无溶剂条件下于200 ℃提供高收率。 rt具有出色的化学,区域和立体选择性。催化效率依次为Zn(BF 4)2 · x H 2 O≫ Cu(BF 4)2 · x H 2 O> Co(BF 4)2 ·6H 2 O≫ Fe(BF 4)2 ·6H2 O> LiBF 4与环己烯氧化物和Zn(BF 4)2 · x H 2 O≫ Co(BF 4)2 ·6H 2 O≫ Fe(BF 4)2 ·6H 2 O> Cu(BF 4)反应2 · x H 2 O,用于氧化二苯乙烯,但AgBF 4是无效的。对于苯乙烯氧化物与苯胺的反应,四氟硼酸金属具有相当的区域选择性(1:99–7:93),并且在环的苄基碳上具有优先反应。与吗啉反应时,观察到区域选择性的逆转(91:1–69:31),有
Efficient solvent-free aminolysis of epoxides under (C4H12N2)2[BiCl6]Cl·H2O catalysis
An efficient and rapid procedure for ring opening of various epoxides with aromatic, aliphatic and heterocyclicamines is developed at room temperature under solvent-free conditions in the presence of (C4H12N2)2[BiCl6]Cl·H2O (1 mol %). This catalyst can be reused several times without losing of its activity.
在(C 4 H 12 N 2)2 [BiCl 6 ] Cl·H 2 O存在下,在室温下在无溶剂的条件下,开发了一种高效快速的方法,可用于芳族,脂族和杂环胺的各种环氧化物的开环。(1摩尔%)。该催化剂可以重复使用几次而不会失去其活性。
An efficient synthesis of 2-amino alcohols by silica gel catalysed opening of epoxide rings by amines
作者:Asit K. Chakraborti、Santosh Rudrawar、Atul Kondaskar
DOI:10.1039/b400588k
日期:——
catalyses the opening of epoxide rings by amines at rt under solvent-free conditions providing an easy method for the synthesis of 2-amino alcohols. Aromatic and aliphatic amines react with cyclohexene oxide with exclusive formation of the trans-2-aryl/alkylaminocyclohexanols in high yields. A complementary regioselectivity is exhibited by aromatic and aliphatic amines during the reaction with styrene
Scope and limitations of montmorillonite K 10 catalysed opening of epoxide rings by amines
作者:Asit K. Chakraborti、Atul Kondaskar、Santosh Rudrawar
DOI:10.1016/j.tet.2004.07.077
日期:2004.10
carbon of other unsymmetrical epoxides. The difference in the internal strain energy of the epoxide ring in cycloalkene oxides and alkene oxides led to selective nucleophilic opening of cyclohexene oxide by aniline in the presence of styrene oxide. Due to the chelation effect, selective activation of the epoxide ring in 3-phenoxy propylene oxide takes place in the presence of styrene oxide leading to preferential