Reglochemistry in Electrophilic Reactions of Propanedlthio-Substituted Allylic Anions Influenced by the γ-Substituents
Journal
Journal of the Chinese Chemical Society
Date Issued
1992
Author(s)
Abstract
The dienyl anion 1f, generated from metallation of 2‐(1,3‐pentadienyl)‐1,3‐dithianc with n‐BuLi in THF, reacted exclusively at the C‐1 position (α‐site) with alkylating agents and ketones, but it showed some tendency toward the C‐3 position (γ‐site) in the reactions with benzyl bromide and aliphatic aldehydes. No reaction at the C‐5 position (ϵ‐site) was observed in any studied case. Examination of the related propanedithio‐substituted allylic anions having various γ‐substituents revealed that the regiochemistry was remarkably influenced by the γ‐substituents and the attacking electrophiles. The electronic effect according to the principle of hard and soft acids and bases is proposed to account for the observed regiochemistry, while the steric factor was minor. Two trienes, obtained by alkylations of the dienyl anion 1f with 4‐bromo‐1‐butene and 5‐pentenyl methanesulfonate, were applicable to intramolecular Diels‐Alder reactions to give bicyclic compounds. Copyright © 1992 The Chemical Society Located in Taipei & Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim, Germany
SDGs
Type
journal article