A STUDY ON SYNTHESIS OF HETEROCYCLES VIA CROSS-CONJUGATED HETEROTRIENES AND FUNCTIONALIZED CARBODIIMIDES AS KEY INTERMEDIATES

点击翻译按钮获取中文摘要

1.Three new types of cross-conjugated heterotrienes have been prepared and their stereoselective diene-transmissive hetero Diels-Alder reactions have been developed for the synthesis of a variety of ring-fused heterocycles such as quinolines, quinazolines, pyrimidopyridazines, pyranopyrimidines, pyranopyridines, pyrrolodiazaphenalenes and pyrroloazaphenalenes. The azatrienes reacted for the initial cycloaddition with reactive dienophiles such as tosylisocyanates, ketenes and vinyl ethers, depending on the substituents on the azatrienes. The second cycloaddition underwent normal electron-demanding Diels-Alder reaction with a variety of common dienophiles.2.Tandem cyclizations strategy of functionalized carbodiimides, which were prepared by the aza-Wittig reaction of iminophosphoranes with isocyanates, has been developed for facile synthesis of a variety of ring-fused nitrogen-heterocyclic compounds such as imidazo-quinolines, imidazoimidazoles, imidazopyrimidines, imidazoquinazolines, imidazothiazines, pyrimidobenzothiazines, quinazolinobenzothiazines, and diazepinoquinolines. They bear a amide-NH group tethering another functional group such as an alkene, an alkyne, an o-bromoarene, a couple of alkenes, or a Michael acceptor. The method [A] includes the initial annulation by intramolecular amine-nucleophilic addition to the carbodiimide-cumulene carbon, followed by the second cyclization by reacting a group of newly formed amine with an inner functional group arranged. The method [B] is a tandem reaction that includes an initial intermolecular addition by a carbon nucleophile, followed by a second intramolecular Michael addition of a newly formed ambident amine or carbon nucleophile center to give quinazolines or quinolines. The third method is a Pauson-Khand type reaction of carbodiimides and ketenimines with alkynes in an intramolecular or intermolecular fashion for the synthesis of pyrrolinone derivatives.