The epimerization of α-chiral hydrazones: Menthonetosylhydrazone
The first preparation of (-)-menthonetosylhydrazone (2) in diastereomerically pure form is reported. Kinetic studies show that 2 is far more susceptible to acid-catalyzed epimerization (∼150x) than is the parent ketone, (-)-menthone (1), a relationship which has not been generally recognized. Conversion of 2 to 1-menthenyllithium (3) using excess butyllithium occurs without detectable epimerization, as determined by analysis of the 1-iodomenthene 5 obtained by treatment of 3 with iodine in-situ. © 1993.
Garner, C., Mossman, B., & Prince, M. (1993). The epimerization of α-chiral hydrazones: Menthonetosylhydrazone. Tetrahedron Letters, 34 (27), 4273-4276. https://doi.org/10.1016/S0040-4039(00)79327-0