Enantiospecific, Nickel-Catalyzed Cross-Couplings of Allylic Pivalates and Arylboroxines
摘要:
We have developed an enantiospecific, nickel-catalyzed cross-coupling of unsymmetric 1,3-disubstituted allylic pivalates with arylboroxines. The success of this reaction relies on the use of BnPPh2 as a supporting ligand for the nickel(0) catalyst and NaOMe as a base. This method shows excellent functional group tolerance and broad scope in both the allylic pivalate and arylboroxine, enabling the preparation of 1,3-diaryl allylic products in high yields with excellent levels of regioselectivity and stereochemical fidelity.
Enantiomerically pure allylic alcohols: preparation by Candida parapsilosis ATCC 7330 mediated deracemisation
摘要:
Biocatalytic deracemisation of racemic allylic alcohols by whole cells of Candida parapsilosis ATCC 7330 resulted in the formation of the (R)-enantiomers in high enantiomeric excesses (up to >99%) and isolated yields (up to 79%). (C) 2008 Elsevier Ltd. All rights reserved.
Optically pure (R) allylic alcohols and (R) 4-phenylbutan-2-ols were prepared via oxidative kinetic resolution using whole cells of Candida papapsilosis ATCC 7330.
Enantioselective reduction of α,β-enones using an oxazaborolidine catalyst generated in situ from a chiral lactam alcohol
作者:Yasuhiro Kawanami、Yudai Mikami、Kazuya Kiguchi、Yuki Harauchi、Ryo C. Yanagita
DOI:10.1016/j.tetasy.2011.10.018
日期:2011.11
The oxazaborolidine catalyst prepared in situ from the chiral lactam alcohol 3 and 4-iodophenoxyborane was found to catalyze the enantioselective reduction of α,β-enones at −40 °C with a high level of enantioselectivity of up to 90% ee.
oxidation of allylicalcohols is challenging to perform in a chemo- as well as stereo-selective fashion at the expense of molecular oxygen using conventional chemical protocols. Here, we report the identification of a library of flavin-dependent oxidases including variants of the berberine bridge enzyme (BBE) analogue from Arabidopsis thaliana (AtBBE15) and the 5-(hydroxymethyl)furfural oxidase (HMFO) and
[reaction: see text] The first example of a kineticresolution process promoted by electrophilic selenium reagents is reported. Racemic allylic alcohols react with half equivalents of a selenenylating agent in methanol leading to the regiospecific formation of the corresponding addition products with a very high level of facial selectivity (from 95:5 to 98:2 dr). The unreacted alcohols can be recovered
Aminocyclopentadienyl Ruthenium Complexes as Racemization Catalysts for Dynamic Kinetic Resolution of Secondary Alcohols at Ambient Temperature
作者:Jun Ho Choi、Yoon Kyung Choi、Yu Hwan Kim、Eun Sil Park、Eun Jung Kim、Mahn-Joo Kim、Jaiwook Park
DOI:10.1021/jo0355799
日期:2004.3.1
tests in the racemization of (S)-4-phenyl-2-butanol showed that 7 is the most active catalyst, although the difference decreased in the DKR. Complex 4 was used in the DKR of various alcohols; at room temperature, not only simple alcohols but also functionalized ones such as allylic alcohols, alkynyl alcohols, diols, hydroxyl esters, and chlorohydrins were successfully transformed to chiral acetates. In