Structure elucidation of the product prepared from the reaction of 3-methyl-5,6-dihydro-2(1H)-pyrazinone and ketones or aldehydes

The condensation products prepared from reactions of 3-methyl-5,6-dihydro-2(1H)-pyrazinone (1) and ketones or aldehydes had previously been assigned the structures 5-alkyl-3-methyl-2(1H)-pyrazinones 3. Current work revealed that the formulas should be revised to 6-alkyl-3-methyl-2(1H)-pyrazinones 2