Fischer carbene complexes . A new tool for heterocyclic synthesis *

This short review covers our contribution in the field of the application of group 6 Fischer carbene complexes toward the synthesis of heterocyclic compounds. Alkenyl and alkynyl carbene complexes are suitable partners in [2+2], [3+2], [4+2], and [4+3] cycloaddition reactions. Moreover, chiral alkenyl carbene complexes react in sequential processes involving an initial Michael addition of a ketone lithium enolate to afford lactones with up to five consecutive stereogenic centers. Based on this strategy, we have devised a new method for the enantioselective synthesis of eight-membered carbocycles.