obsolete 6-(4-methyl-2-oxopentyl)-4-hydroxy-2-pyrone synthase activity (obsolete GO:0102775)
OBSOLETE. Catalysis of the reaction: 2 H+ + isovaleryl-CoA + 3 malonyl-CoA = 6-(4-methyl-2-oxopentyl)-4-hydroxy-2-pyrone + 4 coenzyme A + 3 carbon dioxide.