Rhodium carbenoid mediated cyclizations of o-alkynyl-substituted .alpha.-diazoacetophenones

o-Alkynyl-substituted α-diazoacetophenones undergo facile cyclization to indenone derivatives upon treatment with catalytic quantities of Rh(II) carboxylates. A variety of structural influences were encountered by varying the nature of the substituent group attached to the alkyne carbon atom. The cyclization reaction involves addition of a rhodium stabilized carbenoid onto the acetylenic π-bond to generate a vinyl carbenoid