Regioselective C−H Activation and Sequential C−C and C−O Bond Formation Reactions of Aryl Ketones Promoted by an Yttrium Carbene

Rare earth carbenes exclusively exhibit Wittig-type reactivity with carbonyl compounds to afford alkenes. Here, we report that yttrium carbenes can effect regioselective ortho-C−H activation and sequential C−C and C−O bond formation reactions of aryl ketones to give iso-benzofurans and hydroxymethylbenzophenones. With MeCOPh, cyclotetramerization occurs giving a substituted cyclohexene. This demonstrates new rare earth carbene reactivity which complements existing Wittig-type reactivity.