Alkyl Cyanoferrates, Cyanocobaltates, and Cyanonickelates as New Reagents for Cross-Coupling with Organic Halides

Thomas Kauffmann; Hubert Nienaber

doi:10.1055/s-1995-3872

Synthesis 1995; 1995(2): 207-211
DOI: 10.1055/s-1995-3872

feature article

© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or commercialization outside the narrow limits set by copyright legislation, without the publisher's consent, is illegal and liable to criminal prosecution. This applies in particular to photostat reproduction, copying, cyclostyling, mimeographing or duplication of any kind, translating, preparation of microfilms, and electronic data processing and storage.

Alkyl Cyanoferrates, Cyanocobaltates, and Cyanonickelates as New Reagents for Cross-Coupling with Organic Halides

Thomas Kauffmann^* , Hubert Nienaber¹

^*Organisch-Chemisches Institut der Universität Münster, Corrensstr. 40, D-48149 Münster, Germany

Abstract

PDF Download All articles of this category

Cyano ate-complexes of unknown structure (the following formulae are based only on the stoichiometry of the educts) are produced in situ by the action of 1-4 equivalents of methyllithium on M(CN)₂ (where M=Fe, Co, Ni) at -78°C. Some of these new reagents are very favorable to cross-coupling with organic halides: coupling with 1-bromononane can be achieved by Me₃Ni(CN)₂Li₃, Me₄Ni(CH)₂Li₄, or Me₄Fe(CN)₂Li₄ in 83-90% yield, and with 1-chlorononane by Me₄Ni(CN)₂Li₄ in 80% yield (Table 1). Me₂Fe(CN)₂Li₂ and Me₃Fe(CN)₂Li₃ couple with α-bromostyrene with similar yields (89 and 84%, respectively) as the homoleptic complexes Me₄FeLi₂ and Me₄CoLi₂ (Table 2), whereas Me₂Co(CN)₂Li₂ and Me₃Co(CN)₂Li₃ are clearly superior to these complexes in their coupling with 1-bromonaphthalene (giving 89 and 95% yield, respectively). Me₃Co(CN)₂Li₃and Me₄Co(CN)₂Li₄ gave coupling products with 1-chloro- and 1-fluoronaphthalene in 77 and 67% yield, respectively. MeCo(CN)₂Li is by far superior to other stoichiometric reagents (Table 4) in the coupling (81%) with 1-bromo-2-phenylethyne (postulated mechanism: Scheme 4). Butyl cyano ate-complexes cause the cross-coupling on 1-bromononane and 1-bromonaphthalene in unsatisfactory yields due to side reactions (Table 1 and 3).

transition metal reagents - cyano ate-complexes - cross-coupling - organic halides - transmetalation

PDF (434 kb)