Remarkable Electronic and Steric Effects in the Nitrile Biotransformations for the Preparation of Enantiopure Functionalized Carboxylic Acids and Amides: Implication for an Unsaturated Carbon−Carbon Bond Binding Domain of the Amidase
作者:Ming Gao、De-Xian Wang、Qi-Yu Zheng、Zhi-Tang Huang、Mei-Xiang Wang
DOI:10.1021/jo070581b
日期:2007.8.1
various functionalized racemic nitriles catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase/amidase-containing microbial whole-cell catalyst, were studied. While the nitrile hydratase exhibits high catalytic efficiency but very low enantioselectivity against almost all nitrile substrates examined, the amidase is very sensitive toward the structure of the amides. The release of the steric crowdedness
Compounds of formula (II), (IIIa) or (IIIb)
(variables are described in the specification) are prepared by fluorination of β,γ-unsaturated alkyl silanes. These compounds are useful as building blocks in the pharmaceutical industry.
Enantioconservative synthesis and ring closing metathesis of disubstituted dialkenic amides
作者:Hélène Sauriat-Dorizon、François Guibé
DOI:10.1016/s0040-4039(98)01432-4
日期:1998.9
Optically pure disubstituted dialkenic amides 2, which are direct precursors of Z-ethylenic pseudopeptides 1, are readily synthesized and then cyclized to lactams 3 in the presence of Grubbs' ruthenium-based metathesis catalysts with total conservation of enantiomeric purity. (C) 1998 Elsevier Science Lid. All rights reserved.
Synthesis of Novel Enantiopure Fluorinated Building Blocks from Acyclic Chiral Allylsilanes
作者:Matthew Tredwell、Kenny Tenza、M Carmen Pacheco、Véronique Gouverneur
DOI:10.1021/ol0518535
日期:2005.9.1
Homochiral,beta-fluorinated gamma,delta-unsaturated carboxylic acids with an allylic fluorinated stereogenic center are available from the corresponding enantiopure allylsilanes. The key step for introduction of the fluorine substituent is an electrophilic fluorodesilylation reaction carried out in the presence of Selectfluor. Reduction of the resulting beta-fluorinated pentenoic acid into the corresponding fluorinated alcohol was also performed leading to the formation of an enantiopure second-generation fluorinated building block.