Search

Treatment of acyclic tetraketone 8 with HF·py in MeCN afforded the pentacyclic system 1 in pinnatoxins with a high selectivity in good yield.

The total synthesis of (±)-15-norsolavetivone, a key intermediate in the synthesis of oxygenated spirovetivane stress metabolites, is described.

Cycloadditions of 3-methoxyfuran (1) with several mono-activated dienophiles gave the endo adducts stereoselectively under the usual conditions in satisfactory yields; two of the adducts were transformed into potential intermediates (7a) and (7b) for the synthesis of (±)-avenaciolide and (±)-isoavenaciolide, respectively.

The total synthesis of the title compounds, examples of the spirovetivane type of phytoalexins in the genus Solanum, by transformation of (±)-15-norsolavetivone and derivatives is described.

The biosynthetic production of rishitin from solavetivone via lubimin oxylubimin has been established on the basis of experiment with (±)-[8,8-2H2]solavetivone.

Feeding experiments with (–)-[12,12-2H2]rishitin (1-D) in healthy potato tuber tissues indicated that metabolism of (1) into rishitin M-2 (3) proceeded with a stereospecific 1,2-migration of an olefinic hydrogen at C-12 of (1) in contrast with formation of rishitin M-1 (2) by direct oxygenation on C-13 of (1).

The title compounds metabolites of rishitin (1a) in healthy potato tuber tissues, are determined to possess structures (2a) and (3a).

Treatment of 4,4-(trimethylenedithio)butanal meso-1,2-diphenylethylene acetal (3) with butyl-lithium gave a high yield of 2,2-(trimethylenedithio)cyclobutanol (8), which was transformed into 2-tetrahydropyran-2-yl-oxycyclobutanone (11), a potential intermediate for the synthesis of 1,4-diketones and cyclopentenones.

1-(βγ-Epoxypropyl)cyclohexan-1-ol (1) and its methyl analogues (2) and (3), when treated with base in 75% aqueous Me2SO, gave the corresponding oxetans (4)–(6) as the main products, while treatment of (1) under anhydrous conditions afforded the oxolan dimer (11) as the sole identified product.