Reactions of 4-oxobutanoic acids as well as their cyclic analogues 3H-furan-2-ones with 1,3-binucleophilic reagent (2-aminophenyl) methanol lead to the formation of 1-R-5H-benzo[d]pyrrolo[2,1-b][1,3]oxazines and 3a-R-2,3,3a-trihydro-5H-benzo[d]pyrrolo[2,1-b][1,3]oxazin1-ones, respectively. Quantum-chemical calculations of the Fukui reactivity indices and local hardness have substantiated the mechanisms of the reactions carried out. According to the calculated values of the Fukui indices, in the (2-aminophenyl)methanol molecule, compared to the hydroxyl, the amino group has a higher nucleophilicity, which suggests that its initial nucleophilic attack on the electrophilic centers of the substrates is more probable. According to the calculations, the carbonyl carbon atoms in the molecules of 3H-furan-2-ones have much more pronounced local hardness compared to both carbonyl carbon atoms of 4-oxo acids, which suggests an initial attack by a harder nucleophilic center, the hydroxyl group of 2-(aminophenyl)methanol. Thus, it has been shown that the structure of the formed benzopyrroloxazine(one)s depends on the studied substrate.