Reference

Preparation of tetrahydro-4H-pyran-4-one by cyclocondensation of 1,5-dihalopentan-3-one

Preparation of tetrahydro-4H-pyran-4-one by cyclocondensation of 1,5-dihalopentan-3-one. Sugise, Ryoji; Kashiwagi, Koichi; Matsura, Tsunao (Ube Industries, Japan). Jpn. Kokai Tokkyo Koho JP 09012567 A2 14 Jan 1997 Heisei, 4 pp. (Japanese). (Japan). CODEN: JKXXAF. CLASS: ICM: C07D309-30. APPLICATION: JP 1995-157902 23 Jun 1995. DOCUMENT TYPE: Patent CA Section: 27 (Heterocyclic Compounds (One Hetero Atom)) Claimed is a process for prepn. of the title compd. (I) by cyclocondensation of 1,5-dihalopentan-3-one in the presence of phosphorates, carboxylic acid compds., and H2O. I, an useful as intermediate in the prodn. of drugs and fine chems., is prepd. in an industrial manner efficiently. Thus, 1,5-dichloropentan-3-one was heated at 100° in aq.In this experiment, several chemicals are used like 3592-25-4 and 29943-42-8 NaH2PO4 and salicylic acid to give 46.4% I. .