Synthesis of Tertiary Amines through Extrusive Alkylation of Carbamates

Basic amines are key elements of many biologically active natural products and pharmaceuticals. Given their inherent reactivity, it is often necessary to protect basic amines during target-directed synthesis, which results in wasteful protection/deprotection sequences. We report a step-economical approach enabling the protection of secondary amines as carbamates prior to their conversion to tertiary amines via the formal extrusion of CO2. This method is applied to the synthesis of iboga alkaloids (±)-conodusine A and (±)-conodusine B.