Diastereoselective palladium(0)-catalyzed azidation of 1-alkenylcyclopropyl esters: asymmetric synthesis of (−)-(1R,2S)-norcoronamic acid
摘要:
Palladium(0)-catalyzed azidation of (1R,2S)-1-(1-alkenyl)2-methylcyclopropyl esters 10a,b proceeds with complete retention of configuration to provide, after reduction of the azide and oxidative cleavage of the allylic double bond, the (1R,2S)-norcoronamic acid 22 (>99% e.e.). (C) 1998 Elsevier Science Ltd. All rights reserved.
Mapping the substrate selectivity of new hydrolases using colorimetric screening: lipases from Bacillus thermocatenulatus and Ophiostoma piliferum, esterases from Pseudomonas fluorescens and Streptomyces diastatochromogenes
作者:Andrew Man Fai Liu、Neil A Somers、Romas J Kazlauskas、Terry S Brush、Frank Zocher、Markus M Enzelberger、Uwe T Bornscheuer、Geoff P Horsman、Alessandra Mezzetti、Claudia Schmidt-Dannert、Rolf D Schmid
DOI:10.1016/s0957-4166(01)00072-6
日期:2001.3
screened a general library of 29 substrates and a chiral library of 23 pairs of enantiomers. All four hydrolases catalysed the hydrolysis of unnatural substrates, but the two lipases accepted a broader range of substrates than the two esterases. As expected, the two lipases favoured more hydrophobic substrates, while the two esterases showed a preference for smaller substrates. Several moderately enantioselective
HYDROCARBYL CARBOXYBETAINE AND METHOD FOR PREVENTING HOFMANN ELIMINATION IN ALKALINE ENVIRONMENT
申请人:NATIONAL CHUNG CHENG UNIVERSITY
公开号:US20170001956A1
公开(公告)日:2017-01-05
A Hydrocarbyl Carboxybetaine represented by Formula (1) is provided:
wherein, n
1
≧0 and n
2
>0, A is a C1-C20 alkyl group when n
1
>0, and A is a single bond when n
1
=0. R
1
, R
2
, R
3
, and R
4
are each independently selected from hydrogen atom, deuterium atom, C1-C20 alkyl group, C2-C20 alkenyl group and C2-C20 alkynyl group; X is selected from SH, SOCH
3
, SCH
3
, NH
2
, SiCl
3
, Si(OCH
3
)
3
, Si(OCH
2
CH
3
)
3
,
Enantioselectivity of Haloalkane Dehalogenases and its Modulation by Surface Loop Engineering
作者:Zbynek Prokop、Yukari Sato、Jan Brezovsky、Tomas Mozga、Radka Chaloupkova、Tana Koudelakova、Petr Jerabek、Veronika Stepankova、Ryo Natsume、Jan G. E. van Leeuwen、Dick B. Janssen、Jan Florian、Yuji Nagata、Toshiya Senda、Jiri Damborsky
DOI:10.1002/anie.201001753
日期:2010.8.16
In the loop: Engineering of the surfaceloop in haloalkanedehalogenases affects their enantiodiscrimination behavior. The temperature dependence of the enantioselectivity (lnE versus 1/T) of β‐bromoalkanes by haloalkanedehalogenases is reversed (red data points) by deletion of the surfaceloop; the selectivity switches back when an additional single‐point mutation is made. This behavior is not observed
Trichlorotitanium and alkoxytitanium homoenolates. Preparation, characterization, and utilization for organic synthesis
作者:Eiichi. Nakamura、Hiroji. Oshino、Isao. Kuwajima
DOI:10.1021/ja00273a032
日期:1986.6
demi-equivalent d'alcoolate de titane (IV) sont plus reactives que I, fournissant des voies d'acces a des hydroxy-4 esters, γ-lactones et cyclopropanecarboxylates. Discussion du mecanisme de formation des homoenolates
Des eseses alcoxytitaniumgenerees par traitement de trichlorotitanio-3propionates d'alkyles (I) avec un demi-equivalent d'alcoolate de titane (IV) sont plus reactors que I, Fournissant des voies d'acces a des hydroxy-4esters, γ-内酯和环丙烷羧酸盐。同烯醇化物形成机制的讨论
The Combination of Benzaldehyde and Nickel‐Catalyzed Photoredox C(sp
<sup>3</sup>
)−H Alkylation/Arylation
作者:Lumin Zhang、Xiaojia Si、Yangyang Yang、Marc Zimmer、Sina Witzel、Kohei Sekine、Matthias Rudolph、A. Stephen K. Hashmi
DOI:10.1002/anie.201810526
日期:2019.2.4
Herein we report a highly selective photoredoxC(sp3)−H alkylation/arylation of ethers through the combination of a photo‐organocatalyst (benzaldehyde) and a transition‐metal catalyst (nickel). This method provides a simple and general strategy for the C(sp3)−H alkylation/arylation of ethers. A selective late‐stage modification of (−)‐ambroxide has also been conducted to demonstrate the applicability