Preparation of β-Amino Esters and β-Lactams from Nitriles via Aldimine-Borane Complexes
摘要:
A one-pot synthesis of beta-amino esters has been achieved in 59-75% yield from aromatic and aliphatic nitrites via the condensation of the corresponding non-enolizable and enolizable aldimine-triethylborane complexes, respectively with methyl trimethylsilyl ketene acetals. Grignard-mediated lactamization of the intermediate beta-amino esters provides the corresponding beta-lactams in the same pot in 58-74% overall yield.
A highly efficient Gilman-Speeter synthesis of 3,4-trisubstituted β-lactams possessing a 4-aryl substituent is described, employing a direct, uncatalyzed Mannich reaction between TMS imines and TMS ketene acetals. The process avoids cryogenic conditions, making it more amenable to process-scale use than related methods for β-lactam synthesis. A Gilman-Speeter diastereoselective version using a sulfinyl