Science of Synthesis

Venturello, P.; Barbero, M., Science of Synthesis, (2006) 8, 1431.

In the preparation of cyclopentenes, e.g. ‌86‌, from 1,1-disubstituted alkenes, potassium hexamethyldisilazanide is the best base for promoting the cyclization of the dibromoalkane intermediates, e.g. ‌85‌ (‌Scheme 43‌).[‌55‌] The reaction proceeds via an alkylidene carbene, which undergoes 1,5-insertion into a C—H bond.

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