The syntheses of siccanochromene-a and the related compounds

✍ Scribed by Shigeo Nozoe; Koichi Hirai

• Publisher: Elsevier Science
• Year: 1969
• Tongue: French
• Weight: 189 KB
• Volume: 10
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)88333-7

✦ Synopsis

Recently, we reported the structural elucidation of siccanochromene-A, _B (1) and presiccanochromenic acid (2) , which were isolated from the cultured broth of the plant pathogenic fungi, Helminthosoorium slccans Drechsler.

He describe here the syntheses of the racemic siccanochromene-A (I), presiccanochromene-A (II) and episiccanochromene-B (X).

The keto ester III, prepared by the reported procedure (3) was converted into the ethylene ketal IV.

The ketal IV was treated with methylsulfinyl carbanion in dimethyl sulfoxlde to afford B-keto sulfoxide which was successively treated with aluminum amalgam in aqueous tetrahydrofuran (4). Condensation of the resulting keto ester V with ethyl diethylphosphonoacetate and sodium hydride in dimethyl sulfoxide gave ag-unsaturated ester VI as a separable mixture of a-