Tandem cross metathesis and intramolecular aza-Michael reaction to synthesize bicyclic piperidines and indolizidine 167E

We have successfully transformed the terminal alkenes of dihydropyridones to the α,β-unsaturated esters by cross metathesis (CM). After detosylation the secondary amides can undergo the intramolecular aza-Michael reaction to give the bicyclic piperidine structures. The stereoselectivity of the aza-Michael reaction is determined by the size of the newly formed ring. With simple transformations we have also achieved the synthesis of indolizidine 167E.