Thieno pyrimidine 7,7-dioxides

Annulation reactions of 5 (X=PPhj) with isocyanates, carbon disulfide or carbon dioxide give rise to pyridino[3 2 4,5]-thieno[3,2-d]pyrimidine derivatives. Interesting selectivity is noted in the reactions of 10 with RNCX(X=0,S) in that when R=alkyl cyclization involving both phosphoranimines occurs whereas when R=aryl cyclilzation involves the phosphoranimine directly attached to the arene and the =CHAr center leaving one phosphoranimine intact. Hydrolysis of the remaining center results in formation of the primary amine. 

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