Diastereoselective α-iminoamine rearrangement: asymmetric synthesis of (R)-(−)- and (S)-(+)-2-benzyl-2-hydroxycyclohexanone
摘要:
A convenient asymmetric synthesis of both (R)-(-)- and (S)-(+)-2-benzyl-2-hydroxycyclohexanones starting from racemic 2-benzyloxycyclohexanone and the chiral auxiliary 1-phenylethylamine is reported. The route involves a [1,3]-sigmatropic shift and a new diastereoselective alpha-iminoamine rearrangement of a 2-benzyl-2-iminocyclohexanamine substrate. (C) 1998 Elsevier Science Ltd. All rights reserved.
Diastereoselective α-iminoamine rearrangement: asymmetric synthesis of (R)-(−)- and (S)-(+)-2-benzyl-2-hydroxycyclohexanone
摘要:
A convenient asymmetric synthesis of both (R)-(-)- and (S)-(+)-2-benzyl-2-hydroxycyclohexanones starting from racemic 2-benzyloxycyclohexanone and the chiral auxiliary 1-phenylethylamine is reported. The route involves a [1,3]-sigmatropic shift and a new diastereoselective alpha-iminoamine rearrangement of a 2-benzyl-2-iminocyclohexanamine substrate. (C) 1998 Elsevier Science Ltd. All rights reserved.
Direct Asymmetric α-Hydroxylation of Cyclic α-Branched Ketones through Enol Catalysis
作者:Benjamin List、Grigory Shevchenko、Gabriele Pupo
DOI:10.1055/s-0037-1611084
日期:2019.1
Enantiopure α-hydroxy carbonyl compounds are common scaffolds in natural products and pharmaceuticals. Although indirect approaches towards their synthesis are known, direct asymmetric methodologies are scarce. Herein, we report the first direct asymmetric α-hydroxylation of α-branchedketones through enol catalysis, enabling a facile access to valuable α-keto tertiary alcohols. The transformation
were synthesized with high enantiopurity by asymmetric decarboxylative chlorination and subsequent nucleophilicsubstitution. We recently reported the asymmetric decarboxylative chlorination of β-ketocarboxylic acids in the presence of a chiral primary amine catalyst to obtain α-chloroketones with high enantiopurity. Here, we found that nucleophilicsubstitution of the resulting α-chloroketones with tetrabutylammonium