Asymmetric α-Alkylation of Cyanocarbolines by Phase-Transfer Catalysis

Significance

Maruoka and colleagues reported an asymmetric alkylation of 1-cyanotetrahydro-β-carbolines 1 using phase-transfer catalyst 3. This transformation allows a general access to a variety of 1,1-disubstituted tetrahydro-β-carbolines 2 with high yield and enantioselectivity. The authors further demonstrated that the cyano group in 2a can be hydrolyzed without loss of enantiopurity to form a tetracyclic hydantoin 4.