An Efficient, Overall [4+1] Cycloadditon of 1,3-Dienes and Nitrene Precursors

作者：Wu Qiong; Hu Jian; Ren Xinfeng; Zhou Jianrong^*

来源：Chemistry - A European Journal, 2011, 17(41): 11553-11558.

DOI：10.1002/chem.201101630

• aziridination
• copper
• cycloaddition
• nitrenes
• ring expansion

Intermolecular cycloadditions of conjugated dienes and nitrene precursors usually produce aziridines. A generally useful method was lacking to directly provide the [4+1] cycloadducts, 3-pyrrolines. We have realized this transformation by using an uniquely active catalyst, copper(II) 1,1,1,5,5,5-hexafluoroacetylacetonate ([Cu(hfacac)(2)]). The method is applicable to a wide array of dienes with good yields. When 1,4-disubsituted dienes are used as substrates, good-to-excellent cis or trans selectivity can be obtained. Interestingly, the cis or trans preference depends on the nature of the substituents, rather than diene geometry. Mechanistic studies reveal that the [4+1] cycloaddition proceeds through diene aziridination and subsequent ring expansion. Among common copper catalysts, only [Cu(hfacac)(2)] can efficiently catalyze both steps, which explains the unique efficiency of the catalyst.

• 出版日期2011-10
• 单位四川大学; 南阳理工学院