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- Title
Kupfer(II)-chlorid-katalysierte 'Carben-Dimerisierung' von 1-Halogeno-1-Lithiocyclopropanen: Ein einfacher Zugang zu Bi(cyclopropylidenen).
- Authors
Loosli, Thomas; Borer, Markus; Kulakowska, Iga; Minger, Andrea; Neuenschwander, Markus; Engel, Peter
- Abstract
Copper(II)-Chloride Catalyzed 'Carbene Dimerization' of 1-Halogeno-1-lithiocyclopropanes: A Simple Access to Bi(cyclopropylidenes) A series of 13 bi(cyclopropylidenes) 11 are prepared in a simple one-pot reaction by halogeno-lithio exchange between 1,1-dibromocyclopropanes 1a- n and BuLi, in most cases at −95°, to give 1-bromo-1-lithiocyclopropanes 2a- n, followed by treatment with CuCl2 at low temperature and a simple workup at room temperature ( Scheme 3c and Table 1). The yields of bi(cyclopropylidenes) 11 strongly depend on reaction parameters, as explicitly shown for the conversion 1f →→ 11f ( Tables 2-8). Mixed couplings between two different carbenoids are possible ( Scheme 4), while diastereoselectivity of the active transition-metal complex seems to be low. The structures of bi(cyclopropylidenes) 11 are confirmed by spectroscopic data as well as by X-ray analysis of an isolated crystalline diastereoisomer of 11k ( Fig. 1).
- Publication
Helvetica Chimica Acta, 1995, Vol 78, Issue 5, p1144
- ISSN
0018-019X
- Publication type
Article
- DOI
10.1002/hlca.19950780509