TOTAL SYNTHESIS OF BASTADIN-2, BASTADIN-3, AND BASTADIN-6

A chemoenzymatic strategy has been developed for the synthesis of bast adins 2, 3, and 6. The requisite dimeric dityrosine and isodityrosine building blocks were successfully prepared by oxidative C-C and C-O ph enolic coupling of mono- and dihalogenated derivatives of tyrosine and tyramine using horseradish and soybean peroxidases. By carefully cont rolling the experimental parameters, the requisite synthons may now be prepared in synthetically useful yields without the exhaustive protec tion and deprotection of the sensitive functional groups.