Lee Jong Seok, Fuchs Philip L
Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
Org Lett. 2003 Jun 26;5(13):2247-50. doi: 10.1021/ol034551g.
Dimethyldioxirane (DMDO) C-H oxidation of ketone 17 to hemiketal 18 (82%), bis-dehydration to vinyl ether 21 (77%), and DMDO again provides C-23 axial alcohol 23 (99%). Routine processing, including a double-stereoselective Sharpless AD reaction (de >98%), gives alcohols 7 and 32. C-23 deoxy substrate 7 undergoes Suarez hypoiodite oxidative cyclization to (natural) beta spiroketal 34, but compound 32, bearing a C-23 silyl ether, generates unnatural spiroketal 33. [reaction: see text]
二甲基二氧杂环丙烷(DMDO)将酮17的C-H氧化为半缩酮18(产率82%),经双脱水反应生成乙烯基醚21(产率77%),再次使用DMDO则得到C-23位轴向醇23(产率99%)。常规处理,包括双立体选择性的夏普莱斯不对称双羟基化反应(de>98%),得到醇7和32。C-23脱氧底物7经苏亚雷斯次碘酸盐氧化环化反应生成(天然的)β-螺环缩酮34,但带有C-23位硅醚的化合物32则生成非天然的螺环缩酮33。[反应:见正文]