Studies on the Synthesis of the C-Glycosidic Part of Nogalamycin, Part 3
摘要:
The addition of the metalated 1,4-dimethoxybenzenes 17a-c to the methyl ketone 14 was investigated in connection with the construction of the C-glycosidic part of nogalamycin. In most reactions, a selectivity towards the undesired Q-isomer 16a was observed, However, the reaction of the lithiated aromate 17c with 14 at low temperatures in THF favored the formation of the desired (R)-alcohol 15a (15a:16a = 4.8:1) in accordance with the chelate model A. The selectivity was considerably enhanced in the addition of the more hindered lithiated naphthalene 18 yielding the (R)-isomer 15b exclusively. Reduction of 15b afforded the dimethylamino compound 19b, a direct precursor of the CDEF-ring system of nogalamycin.
Studies on the Synthesis of the C-Glycosidic Part of Nogalamycin, Part 3
摘要:
The addition of the metalated 1,4-dimethoxybenzenes 17a-c to the methyl ketone 14 was investigated in connection with the construction of the C-glycosidic part of nogalamycin. In most reactions, a selectivity towards the undesired Q-isomer 16a was observed, However, the reaction of the lithiated aromate 17c with 14 at low temperatures in THF favored the formation of the desired (R)-alcohol 15a (15a:16a = 4.8:1) in accordance with the chelate model A. The selectivity was considerably enhanced in the addition of the more hindered lithiated naphthalene 18 yielding the (R)-isomer 15b exclusively. Reduction of 15b afforded the dimethylamino compound 19b, a direct precursor of the CDEF-ring system of nogalamycin.