Synthsis and Oxidation of N-Aminquinazolones Aminoquina Zolones

In this thesis we were dealing with studying the intermolecular addition reaction of N-nitrens to a remote 2, 4-dimethoxyphenyl ring. from this study we found that, the nature of the product from the intermolecular addition of the N-nitrene to the dimethyoxyphenyl ring, appeared to be critically dependent on the length of the chain connecting this, 2, 4-dimethoxyphenly ring to the quinazoline ring.However, oxidation of N-aminoquinazolones (138) and (143) (where the number of carbon between the dimethyoxyphenyl ring and the quinazolone ring is just (2)) gave the 1H-azepines (140) (144) respectively. from this result it was clear that;a) although N-nitrenes derived from oxidation of 3-aminoquinazolones have a preference for intermolecular reaction via a 7-memebered transition state, increased nucleophilicity in the trap can allow reaction via a 6-membered transition state,b) Inversion of the azepine ring requires a simultaneous inversion at the ring nitrogen and this accounts for the high energy barrier involved.To encourage nitrene attack as indicated in (153) and to reduce the competitive electrophilic attack at the activated para-position of the dimethoxyphenly ring, we synthesized and oxided the dimethyl analogue of (145). In this case, a product (155) was isolated in 55% yield by oxidation with LTA in methanol whose spectroscopic properties indicated to be analogous to that of (152).Further crystallization from ethyl acetate-pet-ether gave a product to which we could confidently assignee the structure (166) from the close similarity to its spectroscopic data to that of (154), but (166) has a dimethycyclohexane ring instead of a cyclopentane ring in (154). The third crystalline product (167) was obtained from either in 11% yield and its structure was confirmed by X-ray crystallography Fig. (95). It seems probable that (167) is formed by further oxidation of (166).In order to study the effect of decreasing the number of the methylene groups linking the aromatic ring to the quinazolone ring that (2) while the trap for the nitrene is still the remote 2, 4-dimethoxyphenyl ring, we synthesized and oxidized the N-aminoquinazolones (187) and (196).Attempted crystallization of the azepine (201) from methanol gave another azepine (203) whose structure is greatly similar to that of (193) obtained on oxidation of (187), giving a great evidence to support its structure. The minor crystalline product was isolated (20%) on leaving the methanol filtrate in the refrigerator for 24 hrs. The structure of this minor product is closely related to that of the para-dienone with an extra-methyl group. The assigned structure (204) accounts for this similarity and for the existence of the extra-methyl group. On setting aside the methanol filtrate at room temperature instead of keeping it in the refrigerator, the para-dienone (205) was isolated instead of the unstable compound (204).