Nucleophilic Vinylic Substitution of 2,2‐Diaryl‐Substituted 1‐Chlorovinyl p ‐Tolyl Sulfoxides With Alkynyllithiums
Tsutomu Kimura, Saya Yamamoto, Chie Takase, Yuka Nishimura, Koto Sekiguchi, Tsuyoshi SatohNucleophilic vinylic substitution (S N V) reactions of 2,2‐diaryl‐substituted 1‐chlorovinyl p ‐tolyl sulfoxides with alkynyllithiums yield 2‐chloro‐substituted conjugated enynes via C sp ─ bond formation. Sulfoxide bearing two 4‐chlorophenyl groups at the 2‐position is highly reactive toward various alkynyllithiums. The reaction proceeds with configuration retention, which suggests that it follows an S N Vπ mechanism. DFT calculations support a concerted S N Vπ pathway involving simultaneous C─C bond formation and C─S bond cleavage, with an activation barrier of 18.7 kcal mol –1 .