The generation of azomethine ylides from the readily accessible hemiaminals 3 and 8 or from iminium salt 10 was studied. Compounds 8 gave anti- and syn-cycloadducts containing the quinocarcin core through a catalyst-free dehydration process.

A new ylide-initiated tandem cyclization reaction based on γ-dialkylation of allylic ylides has been realized, delivering a series of [3.3.0] oxa-bicyclic dienes in high yields with perfect diastereoselectivity.

Azomethine ylides were generated from Schiffs bases of S-allylcysteine methyl ester and their intramolecular 1,3-dipolar cycloadditions were studied. These reactions led to the synthesis of thieno[3,4b]pyrrole derivatives in good yield.

A catalytic method involving carbenoid insertion onto dihydroimidazoles is reported for the generation of dihydroimidazolium ylides, and their subsequent diastereoselective cycloaddition to form pyrrolo[1,2-a]imidazoles © 2009 Elsevier Science. All rights reserved ———

A direct and facile synthesis of highly functional 5-aza-spiro[2,4]heptanes, a valuable structural motif for drug discovery, is developed via catalytic asymmetric 1,3-dipolar cycloaddition of cyclopropylidene acetate and azomethine ylides for the first time.

Abstract Ruthenium(II)-catalyzed enantioselective C–H functionalization reactions of sulfoximines with sulfoxonium ylides are described. The combination [RuCl2(p-cymene)]2 and a pseudo-C 2-symmetric binaphthyl monocarboxylic acid furnished the S-chiral products in 76:24 to 92:8 er.

Reaction of 4-hydroxy-7-methoxy-2(lH)-quinolone (1) with iodosobenzenes, prepared in situ from the dichloroiodo compounds 2a,b, afforded the iodoniumylides 3a,b in good yields. Their thermal rearrangement produced the 3-iodo-4-aryloxy-quinolones 4a,b. Reductive -deiodinatton of 4a,b gave the corresponding arylethers 5a,b. By photocyclization 4a as well as 5a yielded the benzofuro-quinolone 6a (...

1,2-Annulated pyrrolo[2,1,5-de]quinolizin-5-ones (cycl[3.3.2]azin-5-ones) 6a-6k, 8a-8b and 9 have been synthesized by one pot tandem reactions of 2-acetyl-N-phenacylpyridinium bromides (1a-1d) with electron-deficient cyclic alkenes (N-alkyl(aryl)maleimides, benzoquinones and naphthoquinone) in the presence of sodium carbonate as a base and tetrakispyridinecobalt(II) dichromate (TPCD) as an oxid...

Alkene cis-trans Ratio, Betaine Mechanism, Cycloaddition Mechanism The cis-trans ratio of the stilbenes formed in Wittig reactions of semistabilised ylides (derived from benzyltri(hetero)arylphosphonium salts in ethanolic ethoxide) with benzaldehyde decreases markedly in the series 2-furyl >2-thienyl >phenyl > 1-methylpyrrol2-yl. The 2-furyl group favours a greater proportion of the ci«-isomer ...