Selective Bromination of Tricyclic Quinazolones
- Country : Uzbekistan
- Subject : Organic Synthesis
Abstract
Bromination of the tricyclic quinazolones – deoxyvasicinone (1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-9-one, 1), mackinazolinone (2,3,4,10-tetrahydropyrido[2,1-b]quinazoline-10-one, 2), 7-nitromackinazolinone (7-nitro-2,3,4,10-tetrahydropyrido[2,1-b]quinazoline-10-one, 3) and their some analogues have been systematically studied. It was found that depending on the reaction conditions and structures of the starting compounds takes place bromination on the aromatic ring, on N1=C2 double bound of pyrimidine ring or on methylene groups of the α-position (C-4). Selective bromination of 7-nitromackinazolinone (3) was investigated by N-bromosuccinimide (NBS) in the presence of benzoyl peroxide (BZP) in anhydrous tetrachloromethane. It was developed the method for monobromination of initial compound. The synthesized optical isomers of (R, S)-4-bromo-7-nitromackinazolinone are quantitatively separated on HPLC column, consisting chiral adsorbent. Bromination direction and a course of the reactions with inorganic bromates, molecular bromine and N-bromosuccinimide were discussed. It was revealed that using allylic brominations method (Wohl-Ziegler Reaction) for compound 3 gives exclusively and in high yield targeted chiral compound - 4-bromo-7-nitromackinazolinones (16).
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