Synthesis and Reactivity of N-heterocumulenes

Article abstract of DOI:10.1021/jo00124a011

A number of N-heterocumulenes bearing the (Me3Si)2CH (BSM) substituent adjacent to the terminal nitrogen atom of the heterocumulene function, namely BSM-N=C=O (2), BSM-N=C=S (3), BSM-N=C=NR (4: R = BSM; 5: R = C6H5), BSM-N=C=CR1R2 (9a: R1 = R2 = C6H5; 9b: R1 = H, R2 = SiMe3; 10: R1 = R2 = CH3; 12: R1 = H; R2 = CH3), and BSM-N=S=O (14), have been synthesized.The synthetic utility of the BSM-N-substituted heterocumulenes has been explored through the creation of a carbanion center at the α position relative to nitrogen.In particular, the following reactions have been studied: (i) the nucleophilic addition of MeLi to compounds 2 and 5, (ii) the MeLi-induced deprotonation of ketene imines 9a,b (this investigation includes the study of the regiochemical output of the addition of electrophiles (H2O, MeI, Me2CHI) to the resulting 1,3-dipoles; and (iii) the TBAF-induced desilylation of compounds 2 and 9a followed by reaction with benzaldehyde.