Konomi Haibara

The structures of macbecin I and II : New antitumor antibiotics

Abstract Macbecin I 1 , C 30 H 42 N 2 O 8 , and macbecin II 2 , C 30 H 44 N 2 O 8 , were shown to be 2,6-disubstituted benzoquinone and hydroquinone derivatives by an oxidation-reduction relationship, UV. 1 H and 13 C NMR spectra. Alkaline methanolysis of 1 gave a 2-aminobenzoquinone derivative 5 , suggesting an ansa-structure for 1 , and acid hydrolysis of 1 gave decarbamoyl products 9 , 10 and 11 , indicative of the location of carbamoyloxy group in allylic position. Spin decoupling studies on 1 , 3 and 5 clarified the partial structures [ A ], [ B ], [ C ] and [ D ]. From their mutual disposition two structures 1a and 1b , were proposed out of which 1a has been selected for the structure of 1 on the basis of the structure of oxidative degradation product 12 . X-Ray analysis of the bromoacetyl derivative of 1 confirmed the above proposed structure and determined the absolute stereochemistry of 1 and 2 .

The structures of macbecin I and II, new antitumor antibiotics

Abstract Structures of macbecin I (1) and II (2), new antitumor antibiotics isolated from the culture broth of Nocardia sp. No. C-14919, have been elucidated as benzenoid ansamycins on the basis of chemical evidence and spectral analyses.