Carbenoid

In chemistry a '''carbenoid''' is a reactive intermediate that shares reaction characteristics with a carbene.<ref>''Organic Chemistry'' john McMurry Brooks /Cole Publishing Company 1988 {{ISBN|0-534-07968-7}}</ref> 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 the boronic ester to give an ate complex. The ate complex undergoes a 1,2-metallate rearrangement to give the homologated product, which is then further oxidised to a secondary alcohol.<ref>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}}</ref>

:500px|Insertion of carbenoid into C-B bond

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.

==See also== * The silicon pendant: Silylenoids

== References == {{reflist}}

Category:Carbenes