Complete Diastereocontrol in Intramolecular 1,3-Dipolar Cycloadditions of 2-Substituted 5-Hexenyl and 5-Heptenyl Nitrones: Application to the Synthesis of the β-Lactam Antibiotic 1β-Methylthienamycin
作者:Michael E. Jung、Binh T. Vu
DOI:10.1021/jo952254m
日期:1996.1.1
3,6-disubstituted perhydrocyclopenta[c]isoxazoles has been investigated. An alkyl or aryl substituent at C2 completely controls the stereochemistry of the ring juncture and, in the case of the 5-heptenyl systems, also the stereochemistry of the 3-methyl group. Thus one stereocenter controls the formation of the other three to give a product with four contiguous stereocenters. The use of an ethylene
研究了2-取代的5-己烯基和5-庚烯基硝基的分子内1,3-偶极环加成反应的非对映选择性,从而得到6-取代的和3,6-二取代的全氢环戊[c]异恶唑。在C 2处的烷基或芳基取代基完全控制环连接处的立体化学,并且对于5-庚烯基系统,还控制3-甲基的立体化学。因此,一个立体中心控制其他三个立体中心的形成,以提供具有四个连续立体中心的产品。在这些体系中使用乙烯酮缩酮可以使反应在更低的温度下进行,这是宝石二烷氧基效应的一个例子。该环加成过程已用于有效的β-内酰胺类抗生素1β-甲基噻吩霉素的有效正式全合成中。