MARKOVNIKOFF 2-STEP HYDRO-LITHIATION OF ALPHA-OLEFINS - TRANSFORMATION OF SECONDARY AND TERTIARY ALKYL PHENYL SULFIDES TO THE RELEVANT ALKYLLITHIUM REAGENTS

The transformation of a number of α-olefins to the relevant secondary and tertiary alkyllithium reagents has been accomplished in two steps by first converting them to the corresponding alkyl phenyl sulfides through their acid-catalyzed reaction with thiophenol, and second by cleaving the sulfides with lithium in tetrahydrofuran (THF). The overall yields ranged from ~35 to 80%, based on the isolated carboxylic acids after carbonation. Secondary and tertiary benzylic alkyl phenyl sulfides have been synthesized by alternative routes and cleaved by lithium naphthalene to the corresponding benzylic type organolithium reagents. Some of them were converted to other organoalkali reagents; e.g., Ph2C(CH3)M (M = Li, Na, K), LiCH(Ph)(CH2)nCH(Ph)Li (n = 3, 4, 5, 6, 10), LiOC(Ph)- (R)CH(Ph)Li (R = CH3, Ph), and LiOCH2CH2CH(Ph)Li. The latter two examples represent cases of dianions formally equivalent to those derived from two-electron reductive opening of oxirane and oxetane rings, respectively. The lithiooxy sulfide PhCH(OLi)CH(Ph)SPh underwent a facile C-S as well as C-O bond fission by lithium naphthalene and was transformed to stilbene dianion (PhCH=CHPh)2-. © 1979, American Chemical Society. All rights reserved.