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A novel rearrangement pathway of 3-alkoxycarbonyl-4-carbamoylisoxazolidines, leading to 1H-pyrrole-2,5-diones by treatment with TBAF, is reported. DFT quantum chemical calculations support the reaction route, controlled by ring strain, which proceeds through the opening of a bicyclic intermediate, with aldehyde extrusion. [ABSTRACT FROM AUTHOR]

Abstract: A general, practical, and efficient reduction of four-, five-, six- and, seven-membered N-alkoxycarbonyl lactams to the aldehyde oxidation state is reported. The reduction methodology involves the hydrozirconation reaction by Cp2Zr(H)Cl under mild conditions and proceeds with very short reaction times and in excellent to good yields. The hydrozirconation of N-alkoxycarbonyl lactams with the Schwartz reagent demonstrated to be the mildest and most general method for the formation of lactamols with a high functional group tolerance. [Copyright &y& Elsevier]