Abstract
WHILE the methoxylated carbon-system of (IV) is conclusively established for certain degradation products of colchicine1,2, the synthesis of such unsymmetrically substituted dibenzcycloheptatrienes, necessary for further work, has hitherto miscarried, because of difficulties which are partly concealed and partly apparent2–4. A synthesis which promises to afford the requisite degree of adaptability has now been found and is based on the oxidation of appropriate 9- or 10-methylphenanthrenes with osmium tetroxide in benzene-pyridine5,6. In a model experiment, 9-methylphenanthrene (I) was thereby oxidized to 9 : 10-dihydroxy-9: 10-dihydro-9-methylphenanthrene (II), m.p. 130-131° (found: C, 79.9 ; H, 6.1 ; C15H14O2 requires C, 79.7 ; H, 6.2 per cent), from which, by cleavage with lead tetra-acetate and renewed cyclization, there was obtained the known 3 : 4 : 5 : 6-dibenzcyclohepta-1: 3 : 5-trien-7-one (III)2. Similarly, 2 : 3 : 4: 7-tetramethoxy-10-methylphenanthrene, m.p. 134–135° (found: C, 73.2 ; H, 6.4 ; C19H20O4 requires C, 73.1 ; H, 6.4 per cent), Was converted via the corresponding 9: 10-dihydro-9 : 10-diol, m.p. 156° (found: C, 66.0 ; H, 6.4 ; C19H22O6 requires C, 65.9 ; H, 6.4 per cent) into the unsaturated ketone (IV), which was identical with the part-product previously obtained1 by oxidizing deaminocolchinol methyl ether with sodium dichromate in acetic acid.
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BUCHANAN, G., COOK, J., LOUDON, J. et al. Synthesis of Colchicine Derivatives. Nature 162, 692 (1948). https://doi.org/10.1038/162692a0
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DOI: https://doi.org/10.1038/162692a0
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