Cm. Yu et al., SELF-REGULATED MOLECULAR REARRANGEMENT - DIASTEREOSELECTIVE ZWITTERIONIC AZA-CLAISEN PROTOCOL, Journal of the Chemical Society. Perkin transactions. I, (2), 1996, pp. 115-116
Treatment of N-but-2-enylpiperidine with acyl halides in the presence
of K2CO3 afforded the corresponding Claisen products with high diaster
eoselectivity depending on the E or Z but-2-enyl geometry.