Ring expansion and vinylic nucleophilic substitution competing for (tert-alkyl)2CC(Li)–Cl in carbenoid chain processes

Autor:	Petra Böhrer, Karsten-Olaf Hennig, Bernhard Schubert, Thomas Menke, Rudolf Knorr, Johannes Freudenreich
Rok vydání:	2014
Předmět:	chemistry.chemical_classification Stereochemistry Organic Chemistry Ether Ring (chemistry) Biochemistry Solvent chemistry.chemical_compound chemistry Yield (chemistry) Drug Discovery Nucleophilic substitution Carbenoid Chain reaction Alkyl
Zdroj:	Tetrahedron. 70:2703-2710
ISSN:	0040-4020
DOI:	10.1016/j.tet.2014.03.004
Popis:	Vinylic nucleophilic substitution (SNV) reactions of unactivated, cyclic α,α-dichloroalkenes [(tert-alkyl)2C CCl2] with aryllithiums (RLi) to give (tert-alkyl)2C C(Cl)–R are presented to be carbenoid chain reactions, which involve the unsaturated Cl,Li-carbenoids (tert-alkyl)2C C(Li)–Cl as transient intermediates. The chains are longer and the overall reactions much slower in tert-butyl methyl ether (t-BuOMe) than in THF as the solvent. In competition with the fast SNV step of these Cl,Li-carbenoids, the Fritsch–Buttenberg–Wiechell (FBW) ring expansion in t-BuOMe (but less so in THF) generates short-lived cyclohexyne species, which are trapped by the accompanying RLi species to yield chlorocyclohexene derivatives [(tert-alkyl)–(Cl)C C(R)–(tert-alkyl)] as the FBW chain products.
Databáze:	OpenAIRE
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