π-Facial selection in intermolecular Diels-Alder reactions: Total syntheses of (+)-actinobolin and (+)-5,6,10-triepi-actinobolin

Article abstract of DOI:10.1021/ja00251a021

Syntheses of both 5,6,10-triepi-actinobolin and the antibiotic actinobolin are described in which a homochiral diene prepared from L-threonine is employed as a key componenet in a Diels-Alder reaction with an acetylenic dienophile. While the Diels-Alder reaction of this diene with methyl propiolate furnished the cycloadduct required for the synthesis of (+)-actinobolin as the minor diastereomer, the completion of the synthesis required but seven additional steps. The steric and stercoelectronic features responsible for the π-facial course of this cycloaddition reaction are discussed along with the various steps required to complete the syntheses of the title compounds.