The reaction of 3,4‐dihydro‐2H‐pyran with oxalyl chloride: Formation and crystal structure analysis of an unexpected bicyclic product

Abstract

in Wiley Online Library (wileyonlinelibrary.com).3,4-Dihydro-2-H-pyran and oxalyl chloride react, depending on the conditions, to keto esters, a pyran-3-carboxylic acid or derivatives thereof, or to an hitherto unknown bicyclic acetal containing a vinyl chloride moiety. The structure of the latter product has been unambiguously elucidated by single-crystal X-ray structure analysis. A mechanism for its formation is proposed.

Synthesis of Furo[2,3-b]pyran-2-ones through Ag(I)- or Ag(I)–Au(I)-Catalyzed Cascade Annulation of Alkynols and α-Ketoesters

“…Despite potential biological properties, only two synthetic methods have been documented in the literature to construct furo­[2,3- b ]­pyran scaffolds. Flower et al reported a protocol of TiCl 4 mediated addition of 3,4-dihydro-2 H -pyran to (2-trimethylsilyl)-ethyl pyruvate, which results in perhydro­[2,3- b ]­pyran derivatives, while Schmidt condensed 3,4-dihydro-2 H -pyran with oxalyl chloride, to give the 2-chloro variant in MeOH at an elevated temperature of 120 °C in 42% yield . However, these two reports were limited to a single example in each case.…”