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3-Acetamidophenyl Acetate의 Fries Rearrangement 반응 연구
김동현, 만노즈 마니캄, 풀라레디 보꾸, 이상윤, 조정석, 정상헌 충남대학교 약학대학 의약품개발연구소 2017 藥學論文集 Vol.32 No.-
Fries rearrangement has been known as highly useful reaction for the synthesis of ortho-or para-hydroxyacylbenzene from phenyl ester in the presence of Lewis acid catalyst. Conventionally, aluminum chloride was used as catalyst. For obtaining N-(4-acetyl-3-hydroxyphenyl)acetamide, 3-acetamidophenyl acetate was subjected to Fries Rearrangement reaction using aluminum chloride. Although the desired N-( 4-acetyl-3-hydroxyphenyl)acetamide was obtained, yield was very low. In addition, regioisomer N-(2-acetyl-5-hydroxyphenyl)acetamide and unexpected N-(2-methyl-4-oxo-4H-chromen-7-yl) acet-amide were obtained. NMR study and conversion to known compollnds confirmed the substitlltion pattern of these phenylacetamides and the structure of chromen-4-ones. Under this Fries Rearrangement condition, formation of chromen-4-one was newly discovered.
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이상윤,최민성,마노즈 마닉캄,풀라레디 보꾸,김동현,정상헌 충남대학교 약학대학 의약품개발연구소 2016 藥學論文集 Vol.31 No.-
Chemical shift variations of benzene ring hydrogens along with introduction of amino, acetamido, chlorosulfonyl and aminosulfonyl functional groups in aniline and indoline systems were comparatively analyzed and utilized for determination of stable conformations of acetamido group and chemical shifts for para-disubstituted benzene ring hydrogens. Upon N-acetylation of aniline, chemical shifts of ortho, meta, and para hydrogens are shifted by 0.81, 0.56 and 0.26 downfield from those of aniline. These variations should be incurred by the inductive effect of acetamido group, since the variations are sequentially reduced along with distance from the acetamido function. Indolines upon N-acetylation showed unusual chemical shift variation for 4-, 6-, 7-, and 8-hydrogens (△δ: 0.09, 0.14, 1.47 and 0.24 downfield shift from those of indoline). The remarkably pronounced downfield shift for 7-hydrogen and the unusually small downshifts for 4-and 6-hydrogens of N-acetylindoline compared to those of acetanilide imply the existence of different conformation of acetyl group resulting in the strong electrostatic field effect other than the inductive effect of acetamido group. Although computation of molecular energy of N-acetylindoline around rotation of acetyl group showed two minimum energy conformations, this unusual downfield shift confirms that the real existed conformation of N-acetylindoline is the structure of carbonyl oxygen and hydrogen at 7-position very close. Considering strong electrostatic field effect of N-acetylindoline, acetanilide only possesses the inductive effect, thus conformation of acetamido group in acetanilide should be the structure with carbonyl oxygen of acetamido located away from ortho hydrogens. Therefore the conformation of functional groups must be carefully considered for determination of the chemical shift of benzene ring hydrogens. Chlorosulfonyl and aminosulfonyl group showed chemical shift variation along with the their inductive effect, thus chlorosulfonyl group normally influenced chemical shifts of 4- (△δ: 0.69), 6- (△δ: 0.71) and 7-(△δ: 0.35) hydrogens of indolines from those of N-acetylindoline as shown in aniline system. With these data analysis of indoline system, chemical shifts of hydrogens of symmetrically substituted para-acetamidobenzenzenesulfonyl analogs were obviously determined.
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