Effect of the α-Methyl Substituent on Chemoselectivity in Esterase-Catalyzed Hydrolysis of <i>S</i>-Acetyl Sulfanylalkanoates
作者:Ish Kumar、Ravinder S. Jolly
DOI:10.1021/ol990544+
日期:1999.7.1
The isomeric compounds 1 and 3, which differ only in the position of a methyl substituent, give opposite chemoselectivities in an esterase-catalyzed hydrolysis reaction. The esterase was chemoselective for the oxoester in 1, but for the thiol ester group in 3. A high enantioselectivity was observed for both 1 and 3.
Clean inversion of secondary mesylates and tosylates is effected by CsF in DMF. A variety of oxygen-, sulfur-, nitrogen-, and carbon-nucleophiles are employable. The reaction conditions have been optimized. The use of CsF in DMF is crucial and the reaction proceeds on the surface of solid CsF. It is suggested that hydrogen bonding between CsF and an active hydrogen of nucleophiles is responsible for the smooth reaction. Cesium carbonate fails to give rise to high specificity of inversion indicative of superiority of CsF. (C) 1997 Elsevier Science Ltd.
BIANCHI, DANIELE;CESTI, PIETRO, J. ORG. CHEM., 55,(1990) N1, C. 5657-5659
作者:BIANCHI, DANIELE、CESTI, PIETRO
DOI:——
日期:——
BABA, NAOMICHI;MIMURA, MITSUO;ODA, JUNICHI;IWASA, JUNKICHI, BULL. INST. CHEM. RES. KYOTO UNIV., 68,(1990) N, C. 208-212