Ionic intermediates lactams

The switter ionic intermediate 248 undergoes an electrocyclic conrotatory ring closure to form the -lactam. 

Imidate salts hydrolysis, 118-144 syn and anti, 120 isomerization, 142 B-lactam, 142 Iminium salts, 211-221 Imino-ethers, 147 lodolactonization, 169 Ionic state of tetrahedral intermediates, 65, 105-106, 119 Ionophore A-23187, 13 Isochromane-3-one, 70 Isocyanate, 300 Isonitrile, 296... 

Abstract The possible utilization of room temperature ionic liquids (RTILs), instead of volatile organic compounds (VOCs), in the electrochemical procedures of organic synthesis has been discussed. The synthesis of p-lactams, the activation of carbon dioxide and its utilization as renewable carbon source and the carbon-carbon bond formation reactions via umpolung of aldehydes (benzoin condensation and Stetter reaction) and via Henry reaction have been selected as typical electrochani-cal methodologies. The results, related to procedures performed in RTILs, have been compared with those performed in VOCs. The double role of RTILs, as green solvents and parents of electrogenerated reactive intermediates or catalysts, has been emphasized. 

Phenylketene generated from phenylacetyl chloride with triethylamine gives [2 + 2] imine cycloaddition with catalysis by the N-heterocyclic carbene prepared by partial electrochemical reduction of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) as solvent gives iraws-p-lactam formation (Eqn (4.92)). The zwitterionic intermediate formed in the reaction is stabiHzed by the highly ionic solvent, which also allows isomerization to form the trans product. The use of such N-heterocyclic carbenes in the catalysis of [2 + 2] cycloadditions of ketenes has been reviewed. ... 

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