Synthesis of the Tetraketide Lactones from the Pikromycin Biosynthetic Pathway

摘要

Synthesis of tetraketide lactones 2 and 3, which are likely to be produced by a model pikromycin polyketide synthase (PKS), has been investigated. The tetraketide lactones with six-membered rings, 2a and 2b, were synthesized successfully by the asymmetric aldol reaction, allylation, and the Re-formatsky reaction. The attempted synthesis of tetraketide lactones with eight-membered rings, 3a and 3b, led to the formation of the compounds 2a and 2b. The synthesis of another tetraketide lactone compounds 35 was attempted with the hope that introducing an additional methyl group would lead to a change in thermodynamic stability. However, it produced the corresponding tetraketide lactone 34 with a six-membered ring.