Synthesis of the C10−C22 Bis-spiroacetal Domain of Spirolides B and D via Iterative Oxidative Radical Cyclization
作者:Daniel P. Furkert、Margaret A. Brimble
DOI:10.1021/ol026605c
日期:2002.10.1
[reaction: see text] A synthetic approach to the novel bis-spiroacetal moiety of spirolides B and D is reported. The strategy hinges upon successive formation of the spirocenters at C15 and C18 by radical oxidative cyclization, followed by base-induced rearrangement of a C19-20 alpha-epoxide to introduce the C19 hydroxyl group.
Synthesis of the 1,6,8-trioxadispiro[4.1.5.2]tetradec-11-ene ring system present in the spirolide family of shellfish toxins and its conversion into a 1,6,8-trioxadispiro[4.1.5.2]-tetradec-9-en-12-ol via base-induced rearrangement of an epoxide
作者:Margaret A. Brimble、Daniel P. Furkert
DOI:10.1039/b412883d
日期:——
mixture of 12a : 12b : 12c. The major bis-spiroacetal 12a underwent stereoselective epoxidation using dimethyldioxirane to alpha-epoxide 33a. Subsequent base inducedrearrangement of this epoxide 33a using lithium diethylamide in pentane afforded allylic alcohol 34a, that was converted to the more thermodynamically favoured homoallylic alcohol 11a upon treatment with lithium pyrrolidinylamide in tetrahydrofuran