Grignard reagents addition heterocyclic aromatic

Substituted 3,4-dihydropyrido[2,3-t/]pyrimidines, available by addition of the corresponding Grignard reagent or hydrogen cyanide to pyrido[2,3- /]pyrimidine (see Section 7.2.2.1.1.5.), are oxidized by potassium hexacyanoferrate(III) (K3(i e(CN)6]) in alkaline solution to give the aromatic heterocycles.295... 

It will be recalled that substituted amino functions are displaced more slowly from phosphorus than halogen at low temperatures. An interesting case in the series of phosphinous halides involves the synthesis of phosphorus heterocycles having ultraviolet spectra that suggest aromatic character (46). Addition of Grignard reagents to the phos-... 

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