Unexpected dramatic substituent effect for tuning the selectivity in the double ring-closing metathesis reaction of N-containing tetraenes. An efficient synthesis of bicyclic izidine alkaloid skeletons

[reaction: see text] A double ring-closing metathesis reaction for the efficient construction of the fused bicyclic izidine alkaloid skeleton was developed. In this reaction, high selectivity was realized by tuning of electronic and steric effects of substituents in the N-containing tetraenes. It was observed that the reactivity of electron-rich carbon-carbon double bonds is higher than that of electron-deficient ones. A brief mechanistic study is also discussed.