Rearrangement of substituted pyrimidin-4-ones under the Vilsmeier-Haack reaction

The article describes the result of our study on rearrangements of four heterocyclic systems with variation of oxygen and nitrogen atoms, in particular, the results of formylation of 2,2-disubstituted hydroquinazolones under the conditions of the Vilsmeier-Haack reaction. A new rearrangement of spiro derivatives of quinazolin-4(3H)-ones was discovered under the action of a formylating reagent with the formation of predicted 1-cyclohex(pent)-1-en-1-ylchinazolin-4-(1H)-ones. The absence of this rearrangement for 2,2-dimethyl-2,3-dihydroquinazolin-4(1H)-one is explained. 6',7',7'-Trimethyl-1',5',6',7'-tetrahydrospiro [cyclohexane-1,2'-pyrrolo[3,4-d]pyrimidine]-4'(3'H)-one is a structural analogue of spiro derivatives of quinazolin-4(3H)-ones; it undergoes a similar rearrangement with the formation of 1-cyclopent-1-en-1-yl-6,7,7-trimethyl-1,5,6,7-tetrahydro-4H-pyrrolo[3,4-d]pyrimidin-4-one when interacting with Vilsmeier-Haack reagent.