A chemoenzymatic strategy has been developed for the synthesis of bastadins 2, 3, and 6. The requisite dimeric dityrosine and isodityrosine building blocks were successfully prepared by oxidative C-C and C-O phenolic coupling of mono- and dihalogenated derivatives of tyrosine and tyramine using horseradish and soybean peroxidases. By carefully controlling the experimental parameters, the requisite synthons may now be prepared in synthetically useful yields without the exhaustive protection and deprotection of the sensitive functional groups.
A Biomimetic Approach to the Discorhabdin Alkaloids: Total Syntheses of Discorhabdins C and E and Dethiadiscorhabdin D
作者:Kelly Marshall Aubart、Clayton H. Heathcock
DOI:10.1021/jo9815397
日期:1999.1.1
The characteristic spirodienone structure of the discorhabdin alkaloids is readily formed by reaction of the tyramine-substituted indoloquinonimines 26, 35, and 36 with cupric chloride, triethylamine, and oxygen. This cyclization provides a possibly biomimetic route to discorhabdins C and E (41 and 42). The unbrominated spirodienone 40 reacts with hydrogen over Pd/C to give enone 46. Bromination at