Direct catalytic enantioselective cross aldol-typereaction of an acetate surrogate was developed using Cu alkoxide-chiral phosphine complexes as catalysts. Chemoselective activation and deprotonation of the donor substrate (acetonitrile) by the soft metal alkoxide in a strongly donating solvent (HMPA) are key to success in this reaction. Useful chemical yields and promising enantioselectivities are
Organocatalysed synthesis of isoxazolines initiated by a chemoselective oxa-Michael reaction of N-BocNHOH
作者:R. Noël、V. Gembus、V. Levacher、J.-F. Brière
DOI:10.1039/c3ob42406e
日期:——
An organocatalysed and chemoselective one-pot oxa-Michael-cyclocondensation reaction of N-BocNHOH to unsaturated α-ketoesters is reported which affords an original entry to enantioenriched 3-isoxazoline carboxylate derivatives as biorelevant heterocyclic frameworks.
Enhanced enantioselectivity of an enzymatic reaction by the sulfur functional group. A simple preparation of optically active .beta.-hydroxy nitriles using a lipase
The enantioselectivity of a lipase-catalyzed hydrolysis was improved by varying the acyl residue into the sulfur functional one, i.e. the beta-(phenylthio)- or beta-(methylthio)acetoxy group, from acetate or valerate to realize satisfactory resolution of beta-hydroxy nitriles using lipase P (Pseudomonas sp.).
A total synthesis of yashabushidiol (1a), a linear diarylheptanoid having 1,3-diol system and its analogues has been achieved by alkynylation of 3-hydroxy-5-phenyl pentanal with substituted phenyl acetylenes. All the compounds have shown significant anti-proliferative activity on human leukemia (THP-1, U-937) and melanoma (A-375) cell lines. Compounds 2a and 2b were found to be most potent with an IC50 of 12.82 mu g/mL and 12.62 mu g/mL, respectively, on THP-1 leukemia cell line. (C) 2009 Elsevier Ltd. All rights reserved.