- Two polymorphs of 4-hydroxypiperidine with different NH configurations
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4-Hydroxypiperidine 1 exists in two crystal forms, tetragonal 1t, space group P4ˉ21c and orthorhombic 1o, space group Fdd2, both with one molecule in the asymmetric unit. The latter form was obtained only rarely and in small quantities. In form 1t, the NH hydrogen is axial, whereas in 1o it is equatorial; the OH group is equatorial in both structures. The packing of both forms involves one hydrogen bond N-H?O and one O-H?N. In solution, NMR spectra indicate the presence of separate axial and equatorial forms (with respect to the OH group) below ca. -53 °C; however, not even at -104 °C, the lowest temperature reached, could any freezing out of the inversion at nitrogen be observed, implying that the energy barrier for this process is (as expected) small. We were unable to convert 1t, which appears to be the more stable form over the whole temperature range up to the melting point, to 1o by heating or via melting and re-cooling (or by any other method), perhaps because the hydrogen-bonding pattern is resistant to change. The crystalline forms 1t and 1o, despite being polymorphs of 1 with different NH configurations, should not be described as "configurational polymorphs" because of the facile interconversion in solution.
- D?ring, Cindy,Na¨ther, Christian,Jess, Inke,Ibrom, Kerstin,Jones, Peter G.
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Read Online
- Can Heteroarenes/Arenes Be Hydrogenated Over Catalytic Pd/C Under Ambient Conditions?
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Hydrogenation of over a dozen aromatic compounds, including both heteroarenes and arenes, over palladium on carbon (Pd/C, 1–100 molpercent) with H2-balloon pressure at room temperature is reported. Analyses using pyridine as a model substrate revealed that acetic acid was the best solvent, as using only 1 molpercent Pd/C provided piperidine quantitatively. Substrate scope analysis and density functional theory calculations indicated that reaction rates are highly dependent on frontier molecular orbital characteristics and the steric bulkiness of substituents. Moreover, the established method was used for the concise synthesis of the anti-Alzheimer drug donepezil (Aricept?).
- Tanaka, Nao,Usuki, Toyonobu
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p. 5514 - 5522
(2020/07/24)
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- BENZOPIPERIDINE DERIVATIVES AND THEIR USE IN THE TREATMENT OF CANCER AND HEMOGLOBINOPATHIES
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A compound of formula I: (I) wherein: n is 1 or 2; p is 0 or 1; R1a, R1b, R1c and R1d are independently selected from H, halo, C1-4 alkyl, C1-4 fluoroalkyl, C3-4 cycloalkyl, C1-4 alkyloxy, NH-C1-4 alkyl and cyano; R2a and R2b are independently selected from the group consisting of: (i) F; (ii) H; (iii) Me; and (iv) CH2OH; R2c and R2d are independently selected from the group consisting of: (i) F; (ii) H; (iii) Me; and (iv) CH2OH; R2e is H or Me; R3a and R3b are independently selected from H and Me; R4 is either H or Me; R5 is either H or Me; R6a and R6b are independently selected from H and Me; A is either (IIa), where R7a is selected from N-linked N-containing C5-7 heterocycyl and (A); or (ii) (IIb), where X is selected from CH2, N H and O, one of R8a and R8b is selected from CI and ethoxy and the other of R8a and R8b is H.
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Page/Page column 50
(2017/09/27)
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- TETRAHYDROISOQUINOLINE DERIVED PRMT5-INHIBITORS
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A compound of formula I wherein: n is 1 or 2: p is 0 or 1; R1 is optionally one or more halo or methyl groups; R2a and R2b are independently selected from the group consisting of: (i) F; (ii) H; (iii) Me; and (iv) CH2OH; R2c and R2d are independently selected from the group consisting of: (i) F; (ii) H; (iii) Me; and (iv) CH2OH; R3a and R3b are independently selected from H and Me; R4 is either H or Me; R5 is either H or Me; R6a and R6b are independently selected from H and Me; A is either (i) optionally substituted phenyl; (ii) optionally substituted naphthyl; or (iii) optionally substituted C5-12 heteroaryl.
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Page/Page column 120
(2016/03/19)
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- SUBSTITUTED HETEROCYCLIC SULFONAMIDE COMPOUNDS USEFUL AS TRPA1 MODULATORS
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The invention is concerned with the compounds of formula I or II: and salts thereof. In addition, the present invention relates to methods of manufacturing and methods of using the compounds of formula I or II as well as pharmaceutical compositions containing such compounds. The compounds may be useful in treating diseases and conditions mediated by TRPA1, such as pain.
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Paragraph 0918; 0919
(2015/04/28)
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- Benzofuran derivatives, pharmaceutical composition containing the same, and a process for the preparation of the active ingredient
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The present invention is a piperazinylalkylbenzofuran derivative of the formula wherein R1 represents a C1-4 alkyl group, R2 stands for a hydrogen atom, X means an oxygen atom, Y is a hydroxyl group, Z represents a hydrogen atom, Ar′ represents a diphenylmethyl group, a pyridyl group, a partially saturated 5-membered heterocyclic group or a phenyl group, n has a value of 0 or 1, and pharmaceutically suitable acid addition salts thereof.
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