Planar chirality: cycloaddition and transannular reactions of optically active azoninones that contain (E)-olefins

Unsaturated nine-membered ring lactams that contain (E)-olefins within the ring are characterized by planar chiral properties. Thus, selective convers ions of the double bond allowed a complete transfer of the planar chiral in formation into new stereogenic centers. The basis of the transformations wa s the high activation barrier that prevented efficient flipping of the doub le bond at room temperature (epimerization pR double left right arrow pS) w ith respect to the ring. Cycloadditions led diastereoselectively to cyclopr opano, epimino, epoxy. and dihydroxy azonanones under mild conditions with moderately high yields. The epoxy azonanones were subjected to regio- and d iastereoselective trans annular epoxide opening/ring contraction sequences to give hydroxy indolizidinones. The regiochemical and stereochemical outco me strongly depends on the configuration of the oxirane and the chiral info rmation of the lactam unit. The so-formed optically active bicycles with de fined substitution patterns should serve as versatile building blocks in al kaloid synthesis.