NEW SYNTHETIC REACTIONS BASED ON 1-METHYL-2-FLUOROPYRIDINIUM SALTS. FACILE CONVERSION OF ALCOHOLS TO THIOALCOHOLS
作者:Ko Hojo、Hiroshi Yoshino、Teruaki Mukaiyama
DOI:10.1246/cl.1977.133
日期:1977.2.5
Facileconversion of alcohols to thioalcohols via thiolesters is described. The synthetic scheme involves (i) preparation of thiolesters (5) by the reaction of ethanethioate anion with 2-alkyloxypyridinium salts (3), formed from 1-methyl-2-fluoropyridinium salt (1) and alcohols, and (ii) subsequent reduction of 5 to thioalcohols. A clean inversion of configuration is noted.
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.
BABA, NAOMICHI;MIMURA, MITSUO;ODA, JUNICHI;IWASA, JUNKICHI, BULL. INST. CHEM. RES. KYOTO UNIV., 68,(1990) N, C. 208-212