Pyran derivativesR 0340 DOI: 10.1002/chin.201229149

Amine-Catalyzed Formal [3 + 3] Annulations of 2-(Acetoxymethyl)buta-2,3-die-noate with Sulfur Ylides: Synthesis of 4H-Pyrans Bearing a Vinyl Sulfide Group. — A DABCO-catalyzed annulation of allenoate (I) and ketone-stabilized ylides (II), (IV), and (VI), in which the sulfur atom of the ylide is transferred into the resulting 4H-pyran is reported. Surprisingly, the behavior of ester-stabilized sulfur ylides, e.g. (X), is found to be quite different. Cyclopropane derivatives (XI) or acyclic compounds are obtained. — (LI, K.; HU, J.; LIU, H.; TONG*, X.; Chem. Commun. (Cambridge) 48 (2012) 23, 2900-2902, http://dx.doi.org/10.1039/c2cc30242j ; Shanghai Key Lab. Funct. Mater. Chem., East China Univ. Sci. Technol., Shanghai 200237, Peop. Rep. China; Eng.) — M. Paetzel

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