T. Shimada et al., CYCLIZATION OF THE ENE REACTION-PRODUCTS FROM HEXAFLUOROACETONE IMINE- SYNTHESIS OF BIS(TRIFLUOROMETHYL)PYRROLIDINE DERIVATIVES, Heterocycles, 40(2), 1995, pp. 753-756
N-Tosylhexafluoroacetone imine reacted as a good enophile with ene com
ponents to give alpha,alpha-bis(trifluoromethyl)homoallylamine derivat
ives. Cyclization of the ene reaction products in the presence of p-to
luenesulfonic acid gave alpha,alpha-bis(trifluoromethyl)pyrrolidine de
rivatives, when the delta position of the homoallylamino group was sub
stituted with an aromatic ring, while no reaction occurred, when subst
ituted with an alkyl group.