Piotr Raubo

Synthetic studies on the pederin family of antitumour agents. Syntheses of mycalamide B, theopederin D and pederin

A general modular approach to the members of the pederin family of antitumour agents is exemplified by syntheses of mycalamide B and theopederin D as well as a formal synthesis of pederin. All three compounds are prepared from 6-lithio-2,3-dimethyl-4-phenylselenomethyl-3,4-dihydro-2H-pyran and 2-(3-chloropropyl)-3,3-dimethyl-3,4-dihydro-2H-pyran-4-one.

A synthesis of 18-O-methyl mycalamide B

Metallated dihydropyran 9 and the dihydropyranone 10 previously used in a synthesis of the insect toxin pederin were adapted to the synthesis of 18-O-methyl mycalamide B, the most potent derivative of the anti-tumour agents isolated from a sponge. Key steps in the synthesis include the oxidation of enol silane 11 from the more hindered face using dimethyldioxirane to introduce the hydroxy group at C-12 and the acylation of 6-lithio-3,4-dihydro-2H-pyran 9 with oxalamide 8 to forge the N-(1-alkoxy-1-alkyl)amide bridge. Biological tests in human tumour cell lines confirm the potent anti-proliferative effect of 18-O-methyl mycalamide B in pM concentrations.

Synthesis of the glycidol (1R,2R)-1-iodo-2-(triphenylsilyloxy)cyclopropane: new rearrangements of 2,3-epoxy-3-(trialkyl/arylsilyl)-propan-1-ols

Reaction of the mesylates of selected glycidols 1b, 5a, 5b and 5c with sodium iodide in acetone has been investigated. The mesylate 1b afforded the iodide 2 and the cyclopropane derivative 3 in a ratio which depended upon the reaction time. Whilst the mesylate 5a provided the iodide 6a as the sole product, the mesylates 5b and 5c gave mixtures of the corresponding unrearranged iodoepoxysilanes 6b and 6c, and the epoxides 7b and 7c.