Trapping of carbolithiation-derived tertiary benzylic α-lithio piperidines with carbon electrophiles: Controlling the formation of α-amino quaternary and vicinal stereocenters.

The interception of carbolithiation-derived tertiary benzylic α-lithio piperidines with carbon electrophiles, under HMPA-mediated conditions, has led to the diastereoselective synthesis of vicinally functionalized piperidines bearing α-amino quaternary stereocenters.

Direct access to functionalized benzotropones, azepanes, and piperidines by reductive cross-coupling of α-bromo enones with α-bromo enamides.

The synthesis of functionalized azepenes and piperidines bearing an α-cycloheptenone or benzotropone derivative has been accomplished through direct reductive cross-coupling of α-bromo eneformamides or enecarbamates with highly versatile α-bromo benzotropone derivatives, under cobalt catalysis. The coupling products have been further elaborated to other synthetically useful aza-heterocyclic frameworks.