Scheme 3.

Biosynthesis of chaetoviridin A (15) and 4′-propargyl-chaetoviridin A (17) using the HR-PKS CazF, the acyltransferase CazE and the caz pyrano-quinone intermediate cazisochromene (14) in the presence of the alkylating cofactor 1 or 2.

Biosynthesis of chaetoviridin A (15) and 4′-propargyl-chaetoviridin A (17) using the HR-PKS CazF, the acyltransferase CazE and the caz pyrano-quinone intermediate cazisochromene (14) in the presence of the alkylating cofactor 1 or 2.