Selectivity in the cycloadditions of carbonyl ylides with glyoxylates: an approach to the zaragozic acids—squalestatins
作者:David M. Hodgson、James M. Bailey、Carolina Villalonga-Barber、Michael G. B. Drew、Timothy Harrison
DOI:10.1039/b004870o
日期:——
Reaction of diazodiketoester 8 with glyoxylates in the presence of catalytic rhodium(II) acetate generates 6,8-dioxabicyclo[3.2.1]octanes 9 and 11 in good yield. Elaboration of 9 provides a suitable alcohol 25 for acid-catalysed rearrangement to give the 2,8-dioxabicyclo[3.2.1]octane skeleton 26 of the zaragozic acidsâsqualestatins. More substituted diazodiketoesters 36 and 40 also undergo highly regio- and diastereoselective cycloaddition with glyoxylates to give the cycloadducts 41, 43 and 44.
在催化量的醋酸铑(II)存在下,二氮二酮酯8与甘油二酸酯反应,以良好产率生成6,8-二氧双环[3.2.1]辛烷9和11。对9的进一步修饰提供了适合的醇25,通过酸催化重排可得到2,8-二氧双环[3.2.1]辛烷骨架26,这是扎戈西酸——角鲨烷抑制剂的结构部分。更多取代的二氮二酮酯36和40也能与甘油二酸酯发生高度区域选择性和立体选择性的环加成反应,生成环加成产物41、43和44。