Investigations concerning the organolanthanide and group 3 metallocene-catalyzed cyclization–functionalization of nitrogen-containing dienes

Organolanthanide catalyzed cyclization–silylation of nitrogen-containing polyunsaturated systems allows access to core structures commonly found in naturally occurring alkaloids. Nitrogen-containing dienes with various substitution patterns were investigated. The method was most successful for substrates with terminal alkenes. Cyclization upon pendant 1,1-disubstituted olefins was not realized under various conditions. Interestingly, sterically hindered sulfonamides, which were previously believed to render the catalyst inactive, were actually compatible with the catalyst, thus affording the cyclized products after prolonged reaction times. Variations using fused ring systems were also investigated.