Synthesis and Ag+-catalyzed cyclization of 2,3-dienamides

Reaction of 1-lithiated methoxyallene and lithiated 3-methyl-1,2-butadiene with isocyanates, RNCO (R=alkyl) followed by hydrolysis affords the dienamides H2CCC(OCH3)C(O)NHR and (CH3)2CCCHC(O)NHR, respectively, in good to excellent yields. Cyclization to 2-(5H)-furanylidenamines or mixtures of these compounds with 1,5-dihydro-2H-pyrrol-2-ones can be achieved with silver acetate or silver nitrate in acetone.