TiF4-mediated biomimetic alkylation-cyclization cascade reaction of 2-trimethylsilylmethyl-1,5-dienes with aldehydes

TiF₄ has proven to be the Lewis acid of choice for promoting the biomimetic addition of 2-trimethylsilylmethyl-1,5-dienes to aliphatic aldehydes with concomitant cyclization. 1,3-cis-Disubstituted methylenecyclohexanes are thus produced in good yields and high diastereoselectivity. The reaction appears to proceed via a highly concerted mechanism involving a chair-like transition state.