Reactivity and Synthetic Applications of Bis(iminophosphoranes). One-Pot Preparation of Pyridoquinazolines and Benzonaphthyridines

Article abstract of DOI:10.1021/jo00051a007

Aza-Wittig reaction of bis(iminophosphorane) 4 with 2 equiv of isocyanate leads directly to pyrido<2,3,4-de>quinazolines 5.Iminophosphoranes 8, available from 4 and 1 equiv of the appropriate isocyanate, react either with 1 equiv of isocyanate or ketene to give pyrido<2,3,4-de>quinazolines 9 or benzo<1,6>naphthyridines 10, respectively.Bis(iminophosphorane) 4 by sequential treatment with aldehydes and isocyanates yielded 2,3-dihydropyrido<2,3,4-de>quinazolines 17.