Halolactonization of N-Acyl-N-(2-cyclohex-1-en-1-yl-6-methylphenyl)glycines: Towards Production of 4,1-Benzoxazoheterocycles
Rail R. Gataullin∗
This study was carried out within the framework of the program ‘New approaches and improvement of known strategies for targeted synthesis of poly-, bi- and monocyclic N,N-, N,O-, S,O-containing heterocycles with the identification of their biological, anticorrosion activities and the development of technology practical implementation of the obtained compounds with the corresponding properties’, state task (topic number 122031400274-4).
A significant influence of the nature of the acyl substituent at the nitrogen atom on the direction of the reaction in the interaction of N-acyl-N-(2-cyclohex-1-en-1-yl-6-methylphenyl)glycines with bromine was found. In the case of the N-benzoyl derivative, along with benzoxazocinone, which is formed through the stages of pseudoallyl halogenation and subsequent lactonization due to the replacement of the bromine atom by the oxygen atom of the carboxyl group, a mixture of axially chiral isomers of spiro-fused 2′-bromocyclohexane-benzoxazepin-3-ones was also obtained. The aR*,R*,R*-isomer of benzoxazepinone, which initially is four times predominant in the reaction mixture, upon dissolution in deuterochloroform, slowly transforms into aS*-conformer until a ratio of 2:1 is established. In the case of the N-acetyl analogue of this glycine, the only heterocycle is the product of 7-exo-halogenlactonization, the benzoxazepinone spiro-fused with 2′-bromocyclohexane and an undetermined configuration of the axial chirality.
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Taher A,
Aderibigbe BA,
Morgans GL,
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Khanye SD,
der Westhuizen L,
Fernandes MA,
Smith VJ,
Michael JP,
Green IR,
van Otterlo WA. L.
Tetrahedron 2013; 69: 2038
28
Jian X,
Liu H.
Electrophilic Cyclization. In Comprehensive Organic Synthesis, 2nd ed., Part 1, Vol. 4, Additions to and Substitutions at C-X π-Bonds
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Knochel P,
Molander GA,
Johnson J.
Elsevier; Amsterdam: 2014: 412-465
