Treatment of acylnitroso hetero Diels-Alder cycloadducts 2 with iron(III) or copper(II) in an alcohol solvent induces ring opening to afford predominantly monocyclic anti-1,4-hydroxamic acids 3. However, treatment of cycloadducts 2 with copper(II) in toluene reverses the stereoselectivity of the ring opening to afford syn-1,4-hydroxamic acids 4. These regio- and stereoselective processes separately
在醇溶剂中用
铁(III)或
铜(II)处理酰基亚硝基杂Diels-Alder环加合物2会引起开环,从而主要提供单环抗1,4-异羟
肟酸3。但是,用
铜(II)处理环加合物2 )在
甲苯中逆转开环的立体选择性,得到syn-1,4-异羟
肟酸4。这些区域和立体选择过程分别提供抗1,4-和syn-1,4-二取代的
环戊烯,同时再生异羟
肟酸从而提高了Diels-Alder环加合物的
化学通用性。