4H-3,1-benzoxazines from o-aminoacylbenzenes

Mediated hydrolysis of benzonitrile initiated by NaBH4

“…However, we found that in conditions, under which, for example, ethylenedioxybenzophenones containing amide fragments in the ortho position readily form the corresponding benzhydrols [2], cyanobenzophenone 1 is converted to 3-phenylphthalide 3 in high yield rather than alcohol 2. This result may be interpreted as a sequence of reduction reactions of the carbonyl group, mediated hydrolysis of the cyano group, and intramolecular cyclization.…”

Synthesis of cyclopropyl-substituted 4H-3,1-benzoxazines from 2-amino-phenyl cyclopropyl ketones and 2-cyclopropanoylaminoacylbenzenes

“…A series of effective methods of synthesis have been developed recently [4][5][6][7][8] by which, in principle, one can obtain a wide range of functionally-substituted 4H-3,1-benzoxazines -potential objects for testing for biological activity. Benzoxazines containing cyclopropane units are missing from the 4H-3,1-benzoxazines synthesized so far.…”

“…Another factor repressing the synthesis of cyclopropyl-substituted benzoxazines is evidently the difficulty of preparing cyclopropane derivatives -the precursors of the required heterocycles. We have shown [8] that substituted 4H-3,1-benzoxazines are formed in high yields from 2-acylaminoacylbenzenes by successive reduction of the ketone function to the corresponding benzyl alcohols followed by cyclization of the latter under the influence of sulfuric or trifluoroacetic acid.…”

“…To confirm our idea we carried out the synthesis of cyclopropyl-substituted analogs of compounds of type A (R 2 or R 3 = cyclopropyl) and studied the possibility of converting them into cyclopropyl-substituted 4H-3,1-benzoxazines according to the methodology proposed previously [8].…”

A new synthetic pathway for 2-quinolones

“…6-N-Phenacylamino-7-cyclopropylcarbonyl-1,4-benzodioxane (3) was obtained from amine 1 as described in our previous work [10] …”