Site-selective diels-alder reactions of 7-(methoxyimino)-4-methylchromene-2,8-dione with alkenes

摘要

Regio- and site-selective Diels-alder reactions of o-quinone monooxime 1 are reported. The electron rich dienophiles 2,4,6,8, and 10 react with the exocyclic diene system of monooxime 1 leading to the coumarin derivatives 3,5,7,9,11, and 12. The electron deficient dienophiles 13a,b and 18 react with the quinoid and the pyrone diene systems of compound 1 affording the cycloadducts 14a,b, 17a,b and 19.