Electrophilic 1,3-C→N− and-N→C− migrations in saturated systems

Abstract

A new type of intramolecular electrophilic rearrangements involving the shift of COOA}k groups from carbon to an N-anionic center is considered. Carbanionic species with COOAIk groups at anionic centers containing no acidic hydrogen react unusually with atkyl(ars'l) iso(thio)cyanates giving carbamates as a result of insertion of RNCX into the C--C bond. The kinetics and mechanism of inserhon of a~'l isocyanates into the C--C bond of the phosphonium zwitterion obtained from triisopropylphosphine and ethyl 2-cyanoacrylate are discussed. The reaction of ct-carbanions derived from N,N-disubstituted amides with methyl trifluoromethanesulfonate result in O-methylation. Some possibilities of back N--*C-migrations are considered.

Reactions of carbanions with 2,4‐dinitrofluorobenzene leading to stable heptatrienide moieties

“…It would be interesting to know what might happen to SCHEME 2 -complex like 3, if instead of labile C H bond, the α-C atom bore loosely bound C(O)OEt group (cf. [2]). To construct such -complex, we reacted 2 with zwitterion 6.…”

Novel reactions of arylmalonate carbanions. The reaction with phenyl isocyanate resulting in carbamates by 1,3-C→N migration of the ethoxycarbonyl group

“…We have earlier described the processes of 1,3 С→N migration of the alkoxycarbonyl groups occurring during the interaction of isocyanates with the carbanions based on phosphorus containing zwitterions, 1,2 esters of phenyl cyanoacetic acid, 3 and pyridinium ylides. 4 The study of the mechanism of these transformations (Scheme 1) showed 5 that the reaction proceeds in two steps, and the introduction of the electron withdrawing substituents into the arylisocyanate ring accelerates the formation of carbamates.…”