A green route to enantioenriched (S)-arylalkyl carbinols by deracemization via combined lipase alkaline-hydrolysis/Mitsunobu esterification
摘要:
Herein we report results of the chemoenzymatic deracemization of a range of secondary benzylic acetates 1a-9a via a sequence of hydrolysis with CAL-B lipase in non-conventional media, combined with esterification of the recovered alcohol according to the Mitsunobu protocol following an enzymatic kinetic resolution (KR). The KR of racemic acetates 1a-9a via an enzymatic hydrolysis, with CAL-B lipase and Na2CO3, in non-aqueous media was optimized and gave high selectivities (E >> 200) at good conversions (C >49%) for all of the substrates studied. This method competes well with the traditional one performed in a phosphate buffer solution. The deracemization using Mitsunobu inversion gave the (S)-acetates in moderate to excellent enantiomeric excess 75% < ee < 99%, in acceptable isolated yields 70% < yield < 89%, and with some variations according to the acetate structure. (C) 2013 Elsevier Ltd. All rights reserved.
Herein we report a new approach to enantiomerically enriched acetates using a lipase-catalyzed hydrolysis in non-aqueous media by alkaline carbonate salts. The use of sodium carbonate in the enzymatic hydrolysis with Candida antarctica lipase B (CAL-B) of racemic acetates shows a large enhancement of the reactivity and selectivity of this lipase. The role of the carbonate salts, the amount and the
SILICON-CONTAINING CONDENSATE, COMPOSITION FOR FORMING A SILICON-CONTAINING RESIST UNDER LAYER FILM, AND PATTERNING PROCESS
申请人:SHIN-ETSU CHEMICAL CO., LTD.
公开号:US20170154766A1
公开(公告)日:2017-06-01
The present invention provides a silicon-containing condensate comprising one or more repeating units selected from a repeating unit shown by the following general formula (A1), a repeating unit shown by the following general formula (A2), and a repeating unit shown by the following general formula (A3),
wherein R
1
represents a group shown by the following general formula (A-1) or (A-2); R
2
and R
3
each independently represent the same group as R
1
, a hydrogen atom, or a monovalent organic group having 1 to 30 carbon atoms other than R
1
.
There can be provided a silicon-containing condensate to give a composition for forming a silicon-containing resist under layer film which can form a resist under layer film with good adhesiveness to any resist pattern, whether the pattern is formed by negative development or positive development.