Mechanism of benzylic substituent hydrogenolysis

Garbisch, Edgar W.; Schreader, Loren.; Frankel, J. J.

doi:10.1021/ja00992a055

Cited by 37 publications

(9 citation statements)

References 11 publications

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“…For several decades, much attention has been paid to the stereochemical courses of this reaction. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Some of the factors which affect the courses of the reaction are the structure of the compound,1-9) the catalyst, [1][2][3]5,[8][9][10][11][12][13][14][15]) the additive, 13,16,17) and the medium. [16][17][18] Mitsui and his co-workers1-3) suggested that the stereoselectivity of this reaction could be ascribed to the free-energy difference at the transition states to responding stereoselectivity of benzylamine derivatives has been studied in detail by only Mitsui and Sato.5) In this paper, we will describe the stereoselectivity of the catalytic hydrogenolysis of optically active 2-methyl-2-phenylaziridine, which has reactive carbon-nitrogen bonds.…”

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confidence: 99%

Studies on Hydrogenolysis. LIV. Catalytic Hydrogenolysis of Optically Active 2-Methyl-2-phenylaziridine

Sugi¹,

Mitsui²

1969

Bulletin of the Chemical Society of Japan

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In order to obtain further information about the catalytic hydrogenolysis of benzyl-type compounds, the hydrogenolysis of optically active 2-methyl-2-phenylaziridine (I) over several group VIII transition metal catalysts was investigated in ethanol under ordinary pressure and at room temperature. 2-Phenylpropylamine (II) was obtained as the main product over all the catalysts. The configuration of II was inverted over the palladium catalyst. However, the hydrogenolysis over the platinum catalyst occurred with a significant retention of the configuration. Further, in the case of Raney nickel and Raney cobalt catalysts, the configurations of II were retained with the low stereoselectivities, and a small amount of 2-phenyl-2-propylamine (III) was also produced in addition to II. These results are attributable to the free-energy difference at the transition nitrogen lone-pair, the catalyst hindrance, and other factors.The SN2-type reaction is favored over the palladium catalyst.On the other hand, the SNi-type reaction is favored over platinum, Raney nickel, and Raney cobalt catalysts, where the radical-cleavage reaction will participate in addition to the SNi-type reaction over the latter two catalysts.The differences in behavior between styrene imines and styrene oxides on the catalyst surface were also discussed.

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confidence: 99%

Studies on Hydrogenolysis. LIV. Catalytic Hydrogenolysis of Optically Active 2-Methyl-2-phenylaziridine

Sugi¹,

Mitsui²

1969

Bulletin of the Chemical Society of Japan

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“…The fragment at m/z 194 might be loss of hydrogen molecule from dihydrox benzene which led to quinonoid form and further loss of hydrogen molecule (−2.0 amu) form –NH like isoproterenol hydrochloride to produce daughter ion m/z 192 as iminium scaffold. The hydrogenolysis of benzylic alcohols over palladium catalyst has been reported in the specifics [20] , [21] , [22] . In view of aforesaid observations, the proposed structure of Imp-II was 4-[2-(propan-2-ylamino)ethyl]benzene-1,2-diol.…”

Section: Resultsmentioning

confidence: 99%

“…The prospects to form Imp-II were proposed based on the structure of impurity and synthetic knowledge on the specific step. In addition, a number of mechanistic studies concerning the catalytic hydrogenolysis of benzyl alcohol derivatives over palladium have been reported [20] , [21] , [22] . Kieboom et al [22] reported that the displacement of primary alcoholic group in benzylic system occurs in S N 2 type and tertiary alcoholic group in S N 1 type.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, isolation, identification and characterization of new process-related impurity in isoproterenol hydrochloride by HPLC, LC/ESI-MS and NMR

Kumar

Devineni

Gajjala

et al. 2017

Journal of Pharmaceutical Analysis

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One unknown impurity (Imp-II) during the analysis of laboratory batches of isoproterenol hydrochloride was detected in the level ranging from 0.04% to 0.12% by high performance liquid chromatography with UV detection. The unknown impurity structure was proposed as 4-[2-(propan-2-ylamino)ethyl]benzene-1,2-diol (Imp-II) using the liquid chromatography--mass spectrophotometry (LC--MS) analysis. Imp-II was isolated by semi-preparative liquid chromatography from the impurity-enriched reaction crude sample. Its proposed structure was confirmed by nuclear magnetic spectroscopy such as 1H, 13C, DEPT (1D NMR), HSQC (2D NMR) and infrared spectroscopy (IR), and retention time and purity with HPLC followed by the chemical synthesis. Due to less removable nature of Imp-II during the purification, the synthetic process was optimized proficiently to control the formation of Imp-II below to the limit<0.12% in the course of reaction. The new chemical route was developed for the preparation of this impurity in required quantity with purity to use as reference standard. The most probable mechanism for the formation of Imp-II was discussed in details.

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“…1-Benzyl-c-2,c-3-diphenylindane 12.Ð H (CDCl 3 ): 2.95 (1 H, dd, J gem 13.9, J 1,CH2 10.3, CH 2 Ph), 3.40 (1 H, dd, J gem 13.9, J 1,CH2 5.1, CH 2 Ph), 3.70 (1 H, t, J 1,2 6.7, J 2,3 7.2, H-2), 3.90 (1 H, m, J 1,2 6.7, J 1,CH2 Deoxygenation of Indan-1-ols with Raney Nickel (W-2).ÐThese reactions were carried out by the general procedure described previously. 10 A mixture of indan-1-ol (0.5 mmol), Raney nickel (6 g) and dry ethanol (20 ml) was hydrogenolysed at 30 psi during 8 h. The ethanolic solution was ®ltered and the solvent removed in vacuo.…”

Section: Methodsmentioning

confidence: 99%

“…Indanes 9 and 10 were synthesized by stereoselective deoxygenation with con®guration retention, 10 starting from indanols 7 and 8 respectively and employing Raney nickel (W-2). Indanol 6 proved resistant to deoxygenation under identical conditions.…”

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confidence: 99%

Diastereoisomeric 1-Benzyl-2,3-diphenylindanes: Stereodirected Synthesis and NMR Spectra

Aguirre¹,

Alesso²,

Iglesias³

et al. 1998

J. Chem. Res.

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Mechanism of benzylic substituent hydrogenolysis

Cited by 37 publications

References 11 publications

Studies on Hydrogenolysis. LIV. Catalytic Hydrogenolysis of Optically Active 2-Methyl-2-phenylaziridine

Studies on Hydrogenolysis. LIV. Catalytic Hydrogenolysis of Optically Active 2-Methyl-2-phenylaziridine

Synthesis, isolation, identification and characterization of new process-related impurity in isoproterenol hydrochloride by HPLC, LC/ESI-MS and NMR

Diastereoisomeric 1-Benzyl-2,3-diphenylindanes: Stereodirected Synthesis and NMR Spectra

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