简单的二元羧酸:己二酸(1),琥珀酸(2)和丙二酸(3);制备了具有两个丙酸基团的更复杂的线性四吡咯:mesobiliverdin-XIIIα(4)和mesobilirubin-XIIIα(5),以及在C 10(6)具有宝石-二甲基的红宝石类似物,其99 C 13 CO 2 H基团。由水和H 2 O-(CD 3)2 SO溶液中的滴定曲线确定其p K a值:羧基碳13图C-NMR化学位移随p H的变化而变化。在H 2 O中具有已知p K a的二酸1-3的滴定曲线用作测定四吡咯二酸4-6的p K a s的校准标准:p K a1 = 3.9,对于4,p K a2 = 5.3 ;p K a1 = 4.2,p K a2 = 4.9(5),p K a1 = 4.7,p K a2 = 5.7H 2 O中的6。
Abstract The biosynthesis of the antibiotic metabolities oosponol and oospoglycol by the fungus Gloeophyllum abietinum has been analysed using 13C-labelled acetate, malonate, serine and formate as precursors and 13C NMR as the analytical method. The polyketide pathway could be confirmed. One carbon of the isocoumarin ring originates from serine.