Synthetic studies toward verrucosidin: Synthesis of (±)verrucosal

✍ Scribed by Larry L Klein

• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 245 KB
• Volume: 27
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)84999-0

✦ Synopsis

Verrucosal, --3, a major degradation product of verrucosidin was synthesized in racemic form by a short and direct route from 4,5-dimethyl-2-furoic acid. The structure and degradation studies of the mycotoxin verrucosidin 1 have recently been describedIa. Although no total synthesis of 1_ has been reported, several approaches2 and one synthesis3 of a similar compound, citreoviridin4, 2, have appeared. Furthermore a recent report describes the preparation of intermediate 3 in chiral form Ib. -In light of these results, we report here our preliminary studies which have led to the preparation of (+-)verrucosal, A, a major degradation product of verrucosidin. -3 0 Our approach involved the Birch-type reductive methylation of 4,5-dimethyl-2-furoic acid, 45. 7 Metal-ammonia reductions of furoic acids have been described by Birch6 and others , and our products were in accord with these reports. A solution of acid 4 in sufficient THF was added to a mixture of anhydrous ammonia and lithium (4 eq., -78'C). After 0.25h, excess CH31 was added and following the usual workup7, a 1:l mixture of CHCjb 1.Lg3 La, COOH z.CH,I