An Efficient and Solvent Free Synthesis of N-Aryl 2,3-Dihydro-4H naphtho-[2,1-e] 1,3-oxazines

Oxazine compounds have proved to have many pharmaceutical applications and most of these compounds now a days are used as drugs. For the importance of this class of heterocyclic compounds we are here investigate the synthesis of new derivatives of 1,3-oxazines using solvent free one pot three component system in a drug discovery program ,so starting from β-Naphthol, formaldehyde and aromatic amines in presence of zarconyl chloride as catalyst. compounds 1-9 were synthesized, Benzo 1,3 diazines (10-14) were also synthesized from their corresponding 1,3 oxazines. These compounds were characterized by IR, some representative by [1] HNMR and were discussed.


Introduction
Due to their importance in biological applications oxazines have drew attention of many researchers to investigate this type of hetrocyclic compounds. these researchers have succeeded to prepare different types of oxazines using different methodologies [1][2][3][4][5][6][7][8][9][10] most of the starting material is anthranilic acid or its derivatives with aldehydes, isocyanate, acetic anhydride or with oxazolones [11]. Some other researchers used phenal, amine and aldehydes to the synthesis of these oxazine compounds [12]. Other researchers used chalcones for the synthesis of this type of compounds [13,14] or from 2-Iodoaryl Azides and Amines [15]. Among the studied reactions of oxazine compounds were opening and reclosing of the oxazine ring which is the other way for the synthesis of new oxazine derivatives [16]. The research work on studying the biological activities of some oxazine compounds revealed that most of these compounds have several pharmacological applications for using these compounds as drugs [17][18][19]. In addition the latest studies on oxazine compounds showed the ability to stop the cancer cell growth and repairing the DNA strands [20] and according to the above facts we studied the synthesis of some new compounds using green technique for this synthesis .These new compounds will be our goal for studying their biological activities in our ongoing drug discovery program.   Table 1.
The physical properties for the synthesized compound were illustrated in Table 2 (Schem 1,2).

Results and Discussion
It is worth to state here that power sonic 405 micro processes -controlled bench-top ultra-sonic cleaner was used for ultrasonic chemical condensation affording nearly the same yield within the same given time which is another green technique for the synthesis of these compounds .As it was mentioned in the experimental part .compounds 10 a,b were prepared and showed the same melting points, for 10a was found; 79-81 published: 81-82 o C, while for 10b it was found 120 0 C the published one at 121-122 0 C with identical IR data [21].

Compound (1)
In which the aryl group is p-Chloro phenyl. The Aromatic protons were 6 types as follows :7.99, 7.83, 7.7.81ppm. for carbon 8 of naphthyl ring, 7.71, 7.7ppm. for proton 5. this ring 7.54, 7.40ppm for protons 6,7 while protons 4 ,3 appeared at 7.12, 7.11 and 7.054, 7.02ppm. Phenyl protons appeared as AB (q) at, 6.79, 6.78 ppm. CH 2 protons of the oxazine ring between oxygen and nitrogen appeared at 5.54, 5.5ppm. and the other CH 2 protons appeared at 4.96, 4.77ppm. protons of naphthyl ring protons appeared as two triplet signals which can be easily differentiated from other protons.

Compound (9) where Ar is (o-methyl, P-Nitro phenyl)
This compound was also giving 3 types of protons of the NMR spectra of naphthyl ring protons resonating at 8.

Compounds (11-14)
The detail of IR data for these compounds were shown in Table  4. The NMR spectra of some selected samples were characterized by the following resonating signals: Table 4: IR data for compounds (11)(12)(13)(14).