BASE-INDUCED CYCLIZATION OF (2<i>R</i>,3<i>R</i>)- AND (2<i>S</i>,3<i>R</i>)-<i>N</i>-2,4-DIMETHOXYBENZYL-<i>N</i>-BIS(ETHOXYCARBONYL)METHYL-2-BROMO-3-HYDROXYBUTYLAMIDE
作者:Masao Shiozaki、Noboru Ishida、Tetsuo Hiraoka、Hiroshi Maruyama
DOI:10.1246/cl.1983.169
日期:1983.2.5
Reaction of (2R,3R)-N-2,4-dimethoxybenzyl-N-bis(ethoxycarbonyl)methyl-2-bromo-3-hydroxybutylamide (6) with DBU yielded bicyclic β-lactam 7 by a direct cyclization, and its diastereomer 8 and unexpected γ-lactam 9 by another non-direct cyclization. Also (2S,3R)-isomer 19 gave 8 as a sole product. On the other hand, reactions of 6 and 19 with NaH advanced to afford azetidin-2-one derivatives via the
(2R,3R)-N-2,4-二甲氧基苄基-N-双(乙氧羰基)甲基-2-溴-3-羟基丁酰胺(6)与DBU反应通过直接环化得到双环β-内酰胺7及其非对映异构体8 和意想不到的 γ-内酰胺 9 通过另一个非直接环化。(2S,3R)-异构体19也得到作为唯一产物的8。另一方面,6 和 19 与 NaH 的反应通过相应的环氧化物得到 azetidin-2-one 衍生物。