Synthetic studies of quinolizidine 195C and derivatives

Sulfur-substituted dihydropyridones prepared by aza-Diels–Alder reactions were converted to the cis-2,6-disubstituted derivatives, which could then proceed through ring-closing metathesis (RCM) and cross metathesis (CM) reactions to give many quinolizidine derivatives, including two epimers of (±)-195C.