A novel thiopyran-4-thione synthesis and crystal structure of a thiopyran-4-thione

Abstract

The zinc(II) chloride catalysed reaction between ethylene trithiocarbonate (1) and dibenzoylacetylene (3) gave the novel 2,3,5,6-tetrabenzoylthiopyran-4-thione (4a) and its structure was elucidated by X-ray crystallography. Treatment of 2,3,5,6-tetrabenzoylthiopyran-4-chalcogenones (4a,b) with triethyl phosphite afforded the bis-annelated furans 1,3,5,7-tetraphenylthiopyrano[2,3-c∶5,6-c′]difuran-8-chalcogenones (5a,b) in almost quantitative yields. The mechanism for this furan formation is discussed.