1999 Volume 47 Issue 5 Pages 656-662
N-Tosyltrifluoroacetaldehyde imine (4) reacted with terminal olefins by only heating together to give the ene reactin products. This means the imine is much more reactive than trifluoroacetaldehyde (2) itself as an enophile. However, 4 was very sensitive to moisture and the yields were low even if it was used without isolation. Further, it did not react with non-terminal olefins. In the course on study of the mechanism of this reaction, we found that N-(2, 2, 2-trifluoro-1-ethoxyethyl)tosylamide (12), obtained by the reaction of trifluoroacetaldehyde ethyl hemiacetal (1) with tosylamide (3) in the presence of titanium(IV) chloride followed by addition of ethanol, reacted in the presence of sodium hydride and titanium(IV) chloride to give the same products from the ene reaction of 4 in much better yields. Interestingly, this reaction proceeded with non-terminal olefins.
