2,3-Dihydro-4H-1,3-oxazin-4-ones, Novel Auxiliaries for the Stereoselective Synthesis of 1β-methylcarbapenems
作者:Do K. Pyun、Won J. Jeong、Hee J. Jung、Jae H. Kim、Jin S. Lee、Cheol H. Lee、Bong J. Kim
DOI:10.1055/s-2001-18778
日期:——
as efficient auxiliaries for the stereoselective synthesis of β-methylcarbapenem intermediate 2. Reformatsky-type reactions of 4-acetoxyazetidinone with α-bromopropionyl dihydrooxazinone 10 provided β-methylazetidinones 4 in high diastereoselectivities. The auxiliaries 9 were also easily removed in the Dieckmann cyclization leading to β-methylcarbapenem skeletons. Practical synthesis of β-methylenolphosphates
二氢恶嗪酮 9 由苄基氰分两步制备,可作为立体选择性合成 β-甲基碳青霉烯中间体 2 的有效助剂。 4-乙酰氧基氮杂环丁酮与 α-溴丙酰二氢恶嗪酮 10 的 Reformatsky 型反应提供了具有高非对映选择性的 β-甲基氮杂环丁酮 4。在导致β-甲基碳青霉烯骨架的Dieckmann环化中,助剂9也很容易去除。从 4-乙酰氧基氮杂环丁酮 3 实际合成 β-亚甲基磷酸酯 2 分三步完成(总产率为 61-77%)。