2-FUNCTIONALIZED FURANS AS PRECURSORS OF VERSATILE CYCLOHEPTANE SYNTHONS

An study on the influence of steric and electronic effects of a functi on attached at C-2 of furans in the yield and diastereoselectivity of [4+3] cycloaddition reactions with oxyallyl cations is presented. In a lmost all studied furans a cis diastereospecificity and a high endo di astereoselectivity is observed. Increasing bulkyness of the function a ttached at C-2 of furans, the endo diastereoselectivity increases, but yield decreases. Increasing the electronic density of the furan syste m, by an electron donating group at C-2, both yield and diastereoselec tivity increase. (C) 1997 Elsevier Science Ltd.