A series of symmetrically substituted 2,3-diaryloxiranes 1 4 (Fig. 1) has been studied as photoprecursors for carbonyl ylides [l 31. The stereochemistry of the adducts obtained on the interception of these 4rzn transient system with a variety of dipolarophiles provides information on the mode(s) of electrocyclic opening of the oxiranes to carbonyl ylides as well as on the mechanism of the 4n + ...

The development of multicomponent reactions (MCRs) designed to produce elaborate biologically active compounds has become an important area of research in organic, combinatorial, and medicinal chemistry. A comparative study of the synthesis of new bis-spiro-oxindolo(pyrrolizidines/pyrrolidines) ring systems by the cycloaddition of azomethine ylides generated by a decarboxylative route from sarc...

The [3+2]-cycloaddition of (trimethylsilyl)diazomethane (7) with 9H-fluorene-9-thione (1) at –60°C yields the spirocyclic 2,5-dihydro-5-trimethylsilyl-1,3,4-thiadiazole 10, which eliminates nitrogen at room temperature to give the 1,4-dithiane derivative 13 by dimerization of the intermediate fluorenethione (trimethylsilyl)methanide (11). This thiocarbonyl ylide can be trapped by 1 to give the ...

The development of multicomponent reactions (MCRs) designed to produce elaborate biologically active compounds has become an important area of research in organic, combinatorial, and medicinal chemistry. A comparative study of the synthesis of new bis-spiro-oxindolo(pyrrolizidines/pyrrolidines) ring systems by the cycloaddition of azomethine ylides generated by a decarboxylative route from sarc...