Stabilization of carbinylcarbocation by and nucleophilic attack upon cyclopropyl and trans-2, trans-3-diphenylcyclopropyl rings. Reduction of (trans-2, trans-3-diphenylcyclopropyl)methanol and (trans-2, trans-3-diphenylcyclopropyl)cyclopropylmethanol
作者:Gong-Xin He、Örn Almarsoon、Thomas C. Bruice
DOI:10.1016/0040-4020(92)85003-w
日期:1992.1
(trans-2,trans-3-Diphenylcyclopropyl)methanol (R1OH) can be reduced to (trans-2,trans-3-diphenylcyclopropyl)methane with NaBH3CN in the presence of (PhO)3PMeI and (trans-2,trans-3-diphenylcyclopropyl)cyclopropylmethanol (R2OH) can be reduced to its hydrocarbon by BH3-BF3 without ring opening. Acid catalyzed H2O elimination from R2OH by CF3COOH is accompanied by concerted ring opening of the diphenylcyclopropyl ring with a late transition state, but S(N)2 iodiation of R2OH with (PhO)3PMeI results in concerted opening of the unsubstituted cyclopropyl ring. The trans-2,trans-3-diphenylcyclopropyl group is less effective than a simple cyclopropyl group in stabilizing an adjacent positive charge.