Stereoselectivity of intramolecular cyclisations of nitrones derived from 3-oxahept-6-enals
作者:Michael B. Gravestock、David W. Knight、Jennifer S. Lovell、Steven R. Thornton
DOI:10.1039/a905802h
日期:——
Intramolecular [1,3]-dipolar cycloadditions of nitrones 33, derived from 3-oxahept-6-enals 7, substituted at either the 4- or 5-position and prepared using a variety of approaches, give good to excellent yields of the cycloadducts 34–37, with good levels of stereoselectivity, especially when the substituent is adjacent to the alkene. The cyclisations appear to proceed via well-defined transition state conformations which should be of predictive value.
分子内[1,3]-双极环加成的亚硝基 33 来自 3-oxahept-6-enals 7,在 4 位或 5 位被取代,采用多种方法制备,可得到收率很高甚至非常好的环加成物 34-37,具有良好的立体选择性,尤其是当取代基邻近烯时。环化似乎是通过定义明确的过渡态构象进行的,这应该具有预测价值。