A series of -cyanoaminosilanes have been found to act as azomethine ylide equivalents. Treatment of these compounds with silver fluoride in the presence of electron-deficient alkynes and olefins gives substituted pyrroles and pyrrolidines in high yield. It was found that A-benzyl-TV-(cyanomethyl) -N-[ (trimethylsilyl)methyl] amine undergoes stereospecific cycloaddition with dimethyl fumarate and maléate. The stereospecificity of the reaction is consistent with a concerted cycloaddition reaction. The cycloaddition behavior of an unsymmetrically substituted -cyanosilylamine with methyl propicíate was also examined and found to react with high overall regioselectivity.The synthetic utility of cyanoaminosilanes as azomethine ylide equivalents was demonstrated by the preparation of a Reniera isoindole alkaloid. The key step in the synthesis involved the reaction of 2-methyl-3-methoxyquinone with iV-methyl-Ai-(cyanomethyl)-iV-[(trimethylsilyl)methyl]amine in the presence of silver fluoride to give 2,5dimethyl-6-methoxy-2H-isoindole-4,7-dione in good yield.

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The first total synthesis of the ergot alkaloid paliclavine and the formal total synthesis of paspaclavine in optically active form are described.

The synthesis of -lactones from the addition products of ketene thioacetal anions and carbonyl compounds has been achieved. A unique phenylselenenyl chloride triggered formation of dithienium ion from ketene thioacetal has been shown to directly afford a doubly protected butenolide system.