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Carbenoid
Introduction
In chemistry a carbenoid is a reactive intermediate that shares reaction characteristics with a carbene [1]. In the Simmons-Smith reaction the carbenoid intermediate is a zinc / iodine complex that takes the form of
- I-CH2-Zn-I
This complex reacts with an alkene to form a cyclopropane just as a carbene would do.
Carbenoids appear as intermediates in many other reactions. In one system a carbenoid chloroalkyllithium reagent is prepared in situ from a sulfoxide and t-BuLi which reacts by an insertion reaction into the C-B bond of a pinacol boronic ester [2].
The enantiopurity of the chiral sulfoxide is preserved in the ultimate product after oxidation of the boronic ester to the alcohol indicating that a true carbene was never involved in the sequence.
References
References
- ↑ Organic Chemistry john McMurry Brooks /Cole Publishing Company 1988 ISBN 0-534-07968-7
- ↑ Iterative Stereospecific Reagent-Controlled Homologation of Pinacol Boronates by Enantioenriched -Chloroalkyllithium Reagents Paul R. Blakemore and Matthew S. Burge J. Am. Chem. Soc.; 2007; 129(11) pp 3068 – 3069; (Communication) doi:10.1021/ja068808s