A facile and efficient synthetic route toward highly substituted 2, 3-dihydrothiopyran-4-ones 2 has been developed via a formal [5C+ 1S] annulation of readily available α-alkenoyl ketene- (S, S)-acetals 1 with sodium sulfide nonahydrated salt (Na2S⊙ 9H2O) and utilized in the synthesis of 2-(4-chlorophenyl)-6-(morpholin-4-yl)-4 H-thiopyran-4-one 5l, an inhibitor of DNA-dependent protein kinase (DNA-PK).
[Hollick, Jonathan J.; Golding, Bernard T.; Hardcastle, Ian R.; Martin, Niall; Richardson, Caroline; Rigoreau, Laurent J. M.; Smith, Graeme C. M.; Griffin, Roger J. Bioorganic and Medicinal Chemistry Letters, 2003 , vol. 13, # 18 p. 3083 - 3086]
