Straightforward Syntheses of Furanomycin Derivatives and their Biological Evaluation
摘要:
Several types of furanomycin analogues were synthesized and investigated with respect to their antibacterial activity. Two different synthetic pathways were developed, based on aldol reactions/ring closing metathesis and an ester enolate Claisen rearrangement. Only the natural product and its desmethyl derivative showed antibacterial activity, pointing towards a narrow structure-activity relationship. (C) 2002 Elsevier Science Ltd. All rights reserved.
报道了一种合成保护的α-氨基酸的通用有效策略。该方法以丙二酸酯衍生物为起始原料,以Cs 2 CO 3为碱在60度下,通过释放CO 2,以中等收率得到α-氨基酸衍生物。该方法学显示了广泛的底物范围(伯酸和仲酸),出色的官能团耐受性和高效率,可在温和的反应条件下提供所需的产物。它还允许构建β和γ-氨基酸以及其他非天然产物。
Enzymatic Removal of Carboxyl Protecting Groups. 1. Cleavage of the <i>tert</i>-Butyl Moiety
作者:Marlen Schmidt、Efrosini Barbayianni、Irene Fotakopoulou、Matthias Höhne、Violetta Constantinou-Kokotou、Uwe T. Bornscheuer、George Kokotos
DOI:10.1021/jo050114z
日期:2005.4.1
A recent discovery that a certain amino acid motif (GGG(A)X-motif) in lipases and esterases determines their activity toward tertiary alcohols prompted us to investigate the use of these biocatalysts in the mild and selective removal of tert-butyl protecting groups in amino acid derivatives and related compounds. An esterase from Bacillus subtilis (BsubpNBE) and lipase A from Candida antarctica (CAL-A)
最近发现,脂肪酶和酯酶中的某些氨基酸基序(GGG(A)X-基序)决定了它们对叔醇的活性,这促使我们研究了这些生物催化剂在温和选择性去除叔丁基保护基中的用途。氨基酸衍生物和相关化合物。枯草芽孢杆菌的酯酶(BsubpNBE)和南极假丝酵母的脂肪酶A (CAL-A)被确定为活性最高的酶,可水解一系列受保护氨基酸的叔丁基酯(例如Boc-Tyr-O t Bu ,Z-GABA-O t Bu,Fmoc-GABA-O t Bu)以高到高收成,并保留Boc,Z和Fmoc保护基完整。
POLYIMIDE PRECURSOR, POLYIMIDE, AND LIQUID CRYSTAL ALIGNING AGENT
申请人:Nagao Masato
公开号:US20120088888A1
公开(公告)日:2012-04-12
To provide a novel polyimide precursor or polyimide which can provide a liquid crystal alignment film having a low volume resistivity, a liquid crystal aligning agent containing these polymers, a liquid crystal alignment film and a novel diamine which is useful as the starting material of these polymers.
A polyimide precursor having polymerized units represented by the formula (1), and characterized by satisfying any one of the following (i) to (iii):
(i) the structure of X, Y or each of them in formula (1) has a group represented by the following formula (2);
(ii) R
2
, R
3
or each of them in formula (1) is a group represented by the following formula (2);
(iii) the structure of X, Y or each of them in formula (1) has a group represented by the following formula (2), and R
2
, R
3
or each of them is a group represented by following formula (2):