R. Gupta, P. Harland, R. J. Stoodley
1984
Citations
0
Influential Citations
44
Citations
Journal
Tetrahedron
Abstract
Abstract A chromatography-free, seven-step synthesis of the title compound ( 3 ) is described. The tetracyclic carbon skeleton is elaborated by a Diels-Alder strategy in which the 6a,7- and 1O.1Oa-bonds are constructed the epoxy-tetrone ( 9 ) and the D-glucose-derived diene ( 10b ) serving as precursors. Interestingly, the cycloaddition reaction leads mainly to the “desired” cycloadduct ( 11b ), revealing a notable diastereofacial reactivity of the diene (10b). Hydrolysis of the cycloadduct ( 11b ) leads to the epoxy-pentone ( 12b ) which is reduced to the dihydroxy-trione ( 13b ). The reaction of the last-cited compound with ethynylmagnesium bromide affords a mixture of the ethynyl-diones ( 20b ) and ( 21b ), the latter compound arising from the precursor (13b) by a prior epimerisation at the 10a-position. The mixture of ethynyldiones ( 20b ) and ( 21b ) is converted into the anthracycline ( 14b ) by the action of lead ( IV ) acetate. By a hydrolysis-hydration sequence, the anthracycline ( 14b ) is transformed into (+)-4-demethoxydaunomycinone (3).