Alcohols immobilized as p-alkoxybenzyl ethers on Wang resins have been subjected to a variety of chemical transformations based on existing functionality (enolate chemistry, carbonyl group reactivity, Mitsunobu inversion, ozonolysis, Heck reactions, etc.), in an effort to test the suitability of this novel resin-bound ether linkage. The modified substrate was released from the resin by mild acid treatment. (C) 1998 Elsevier Science Ltd. All rights reserved.
Intramolecular reductive amination strategy to the synthesis of (R)-N-Boc-2-hydroxymethylmorpholine, N-(3,4-dichlorobenzyl)(R)-2-hydroxymethylmorpholine, and (R)-2-benzylmorpholine
作者:Rajiv T. Sawant、Suresh B. Waghmode
DOI:10.1016/j.tet.2010.01.047
日期:2010.3
(R)-N-Boc-2-hydroxymethylmorpholine, N-(3,4-dichlorobenzyl)(R)-2-hydroxymethylmorpholine, and (R)-benzylmorpholine has been achieved by employing proline-catalyzedasymmetric α-aminooxylation of aldehyde and palladium-catalyzed intramolecular reductive amination of azido aldehyde as the key steps.
(HHDHs) possess an unnatural activity of introducing functionalities such as N3, CN, NO2 etc., into a molecule through the ring-opening reaction of epoxides. The enantioselectivity of HHDHs is substrate-dependent and not always high enough for synthetic applications. B-group of HHDHs has been neglected in the past, due to observed low enantioselectivity based on performance on a relatively limited number
Azidolysis of epoxides catalysed by the halohydrin dehalogenase from Arthrobacter sp. AD2 and a mutant with enhanced enantioselectivity: an (S)-selective HHDH
Halohydrin dehalogenase from Arthrobacter sp. AD2 catalysed azidolysis of epoxides with high regioselectivity and low to moderate (S)-enantioselectivity (E = 1-16). Mutation of the asparagine 178 to alanine (N178A) showed increased enantioselectivity towards styrene oxide derivatives and glycidyl ethers. Conversion of aromatic epoxides was catalysed by HheA-N178A with complete enantioselectivity, however the regioselectivity was reduced. As a result of the enzyme-catalysed reaction, enantiomerically pure (S)-beta-azido alcohols and (R)-alpha-azido alcohols (ee >= 99%) were obtained. (C) 2016 Published by Elsevier Ltd.
Practical synthesis of (R)-γ-amino-β-hydroxybutanoic acid (GABOB) from (R)-epichlorohydrin