The stereochemistry of the intramolecular electrophilic attack of an aldehyde on a carbon-tin bond

Abstract

The cyclopentane-forming reaction ( 20–43) of (4 RS ),5 SR )-2, 2,4-trimethyl-5-trimethylstannylhexanal takes place with retention of configuration at the carbon atom undergoing electrophilic substitution, in contrast to similar cyclopropane-forming reactions (e.g. 47–48), which take place with inversion of configuration. The hydride transfer ( 24–45) of the 4 RS ,5 RS diastereoisomeric hexanal takes place from a conformation with hydride anti to the stannyl group. In the case of reactions which might have formed four-membered rings, fragmentation takes place ( 16–28 and 17–30). The presence of a phenyl ring on the carbon carrying the stannyl group interferes with the reactions designed to test the stereochemistry of the S E2 reaction, diverting the reaction to the formation of tetralins ( 10–26 and 34–38) or benzcycloheptenes ( 34–37).