Stereospecific total synthesis of the antiviral agent hamigeran B - Use of large silyl groups to enforce facial selectivity and to suppress hydrogenolysis
Stereoselective hydrogenation of the tetrasubstituted double bond in enone 1 is possible, provided the keto group at C7 is first removed and the α face is blocked by tert-butyldimethylsiloxy groups at positions 10 and 11. The resulting product 2 is easily
Synthesis of (+/-)-hamigeran B, (-)-hamigeran B, and (+/-)-1-epi-hamigeran B: use of bulky silyl groups to protect a benzylic carbon-oxygen bond from hydrogenolysis.
Enone 42 was converted into diene 56, which was then subjected to hydrogenation. Use of the tert-butyldimethylsiloxy groups enforces facial selectivity and protects the C(5) oxygen from hydrogenolysis. The resulting product (55) is easily converted into hamigeran B (1), a marine natural product with powerful activity against herpes and polio viruses. Optically pure enone 73 was made by use of a Meyers' auxiliary and converted into (-)-hamigeran B with the natural absolute configuration.
Clive, Derrick L J,Wang, Jian
p. 2773 - 2784
(2007/10/03)
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