First asymmetrie synthesis of frans-3,4-dimethyl-4-arylpiperidines
The first asymmetric synthesis of the trans-3,4-dimethyl-4-arylpiperidine opioid antagonist scaffold is reported. C-3 stereochemistry was established via CBS reduction and stereoselective anti-SN2′ cuprate displacement of the derived allylic phosphonate. The resultant vinyl bromide was then elaborated to the target compound by Suzuki coupling and frans-selective 4-methylation. Extension of this methodology should allow general enantioselective access to highly substituted piperidine ring systems.