C-, N-, and/or O-methylation products were generated from 11H-isoindolo[2,1-a]quinazoline-5-one upon treatment with NaH followed by iodomethane under air, and possible recrystallization from methanol. Two products were fully characterized by NMR and X-ray diffraction analysis. In accordance with the HSAB principle, this soft methylating agent (MeI) leads mainly to the C,C-dimethylated product 11,11-dimethyl-11H-isoindolo[2,1-a]quinazoline-5-one, which was previously not observed, beside the N-methylated product, in a procedure using methyl tosylate as a hard methylating agent of the same substrate in the initial absence of a base. A mechanism is finally proposed for the formation of methyl 2-(3-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)benzoate as an oxidation side product.
Isoindoles, methylation processes, oxidative ring opening, quinazolines
BAGLAI, IAROSLAV; MARAVAL, VALERIE; VOITENKO, ZOIA VSEVOLODIVNA; DUHAYON, CARINE; VOLOVENKO, YULIAN MIHAILOVICH; and CHAUVIN, REMI
"On the peculiar reactivity of a C,N-annelated isoindole core,"
Turkish Journal of Chemistry: Vol. 38:
1, Article 12.
Available at: https://journals.tubitak.gov.tr/chem/vol38/iss1/12