Self-Assembly and Structure of Diacetyl-2-Methyl-4,6-bis(phenylethynyl)Tetrahydro-2H-Pyran-2-Ylacetate

Abstract

Unusual condensation of phenylpropargyl aldehyde with acetylacetone in acetonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene as a catalyst is described. It proceeds at room temperature with the formation of a racemic mixture of (2S,3S,4S,5S,6S)- and (2R,3R,4R,5R,6R)-3,5-diacetyl-2-methyl-4,6-bis(phenylethynyl)tetrahydro-2H-pyran-2-ylacetate instead of expected 3-(3-phenylprop-2-in-1-ylidene)pentane-2,4-dione. The X-ray diffraction and NMR studies of the molecular and crystal structures of this compound reveals an anometric effect that manifests itself at the axial position of the acetoxy group relative to the six-membered heterocycle.