RESUMO
A divergent synthesis of 10 icetexane natural products based on a proposed biogenetic cationic ring expansion of a reduced carnosic acid derivative is described. Of these icetexanes, (+)-salvicanol, (-)-cyclocoulterone, (-)-coulterone, (-)-obtusinoneâ D, and (-)-obtusinoneâ E have been synthesized for the first time. In addition, the hypothesis for the non-enzymatic biogenesis of benzo[1,3]dioxole natural products has been experimentally investigated. Additional experimental evidence for the abiotic formation of the methylenedioxy unit is provided, as photolysis of the quinone (+)-komaroviquinone resulted in the formation of the [1,3]dioxole-containing natural product (-)-cyclocoulterone and (+)-komarovispirone.
Assuntos
Produtos Biológicos/síntese química , Diterpenos/síntese química , Produtos Biológicos/química , Cristalografia por Raios X , Reação de Cicloadição , Diterpenos/química , Modelos Químicos , Conformação Molecular , Fotólise/efeitos dos fármacos , Quinonas/síntese química , Quinonas/química , EstereoisomerismoRESUMO
A protecting-group-free route to (-)-taiwaniaquinone F based on a ring contraction and subsequent aromatic oxidation of a sugiol derivative is reported. In addition, the first synthesis of (+)-taiwaniaquinol A is reported via short time exposure of (-)-taiwaniaquinone F to sunlight triggering a remote C-H functionalization. The hypothesis that the biogenesis of some methylenedioxy bridged natural products could proceed via similar nonenzymatic mechanisms is presented.