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Search Results: 1 - 10 of 209775 matches for " Arnold L. Rheingold "
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Chiral Camphor-Based 1,3- and 1,4-Amino Alcohols and Aminodiols as Ligands for Diethylzinc Addition to Aldehydes  [PDF]
Olusegun B. Olubanwo, James A. Golen, Arnold L. Rheingold, Vesa Nevalainen
International Journal of Organic Chemistry (IJOC) , 2018, DOI: 10.4236/ijoc.2018.82018
Abstract: Syntheses of (1R,2S,3R,4S)-1,7,7-trimethyl-2-pyridin-2-ylmethylbicyclo[2.2.1]-heptane-2,3-diol (7), (1R,2S,3R,4S)-1,7,7-trimethyl-2-[(6-methyl)-pyridin-2-ylmethyl-bicyclo-[2.2.1]heptane-2,3-diol (13), and (1R,2S,2’R,4R)-1,7,7-trimethyl-2-piperidin-2-ylmethyl-bicyclo[2.2.1]heptan-2-ol (19b) from commercially available (d)-camphor (1) are described. Key steps of the syntheses involved substrate-controlled diastereoselective alkylation and platinum oxide-catalyzed hydrogenation reactions. These compounds, and other intermediate amino alcohols in their syntheses, were successfully utilized as ligands in enantioselective diethyl zinc (Et2Zn) addition to benzaldehyde with moderate enantioselectivity.
2,2,3,3,5,5,6,6-Octa-p-tolyl-1,4-dioxa-2,3,5,6-tetragermacyclohexane dichloromethane disolvate
Monika L. Amadoruge,Arnold L. Rheingold,Charles S. Weinert
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809032012
Abstract: The title compound, C56H56Ge4O2·2CH2Cl2 or Tol8Ge4O2·2CH2Cl2 (Tol = p-CH3C6H4), was obtained serendipitously during the attempted synthesis of a branched oligogermane from Tol3GeNMe2 and PhGeH3. The molecule contains an inversion center in the middle of the Ge4O2 ring which is in a chair conformation. The Ge—Ge bond distance is 2.4418 (5) and the Ge—O bond distances are 1.790 (2) and 1.785 (2) . The torsion angles within the Ge4O2 ring are 56.7 (1) and 56.1 (1)° for the Ge—Ge—O—Ge angles and 43.9 (1)° for the O—Ge—Ge—O angle.
2-Amino-4-methylpyridinium trifluoroacetate: a monoclinic polymorph
Mehrdad Pourayoubi,Maryam Toghraee,Arnold L. Rheingold,James A. Golen
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810008408
Abstract: The title salt, C6H9N2+·C2F3O2 , is a monoclinic polymorph of a previously reported structure [Hemamalini & Fun (2010). Acta Cryst. E66, o781–o782]. In the crystal structure, the cations and anions are linked by two different types of N—H...O hydrogen bonds, forming cation–anion pairs. These pairs are hydrogen bonded to neighbouring pairs via another N—H...O hydrogen bonds involving an H atom of the NH2 group and one of the O atoms of the COO group into a chain extended along the b axis.
N-(2-Fluorobenzoyl)-N′,N′′-bis(4-methylphenyl)phosphoric triamide
Mehrdad Pourayoubi,Atekeh Tarahhomi,Arnold L. Rheingold,James A. Golen
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811009640
Abstract: The P atom in the title compound, C21H21FN3O2P, is in a tetrahedral coordination environment and the environment of each N atom is essentially planar (sums of angles = 359.7, 359.9 and 358.4°). The phosphoryl and carbonyl groups adopt anti orientations with respect to each other. In the crystal, adjacent molecules are linked via N—H...O=P and two N—H...O=C hydrogen bonds into an extended chain parallel to the a axis.
Diphenyl (2-chlorobenzylamido)phosphate
Mehrdad Pourayoubi,Poorya Zargaran,Arnold L. Rheingold,James A. Golen
Acta Crystallographica Section E , 2011, DOI: 10.1107/s160053681004955x
Abstract: In the title compound, C19H17ClNO3P, the P atom exhibits a distorted tetrahedral configuration. In the crystal, pairs of intermolecular N—H...O(P) hydrogen bonds form centrosymmetric dimers.
(3aS,7aS)-5-[(S)-3,3,3-Trifluoro-2-methoxy-2-phenylpropanoyl]-2,3,4,5,6,7-hexahydro-1H-pyrrolo[3,4-c]pyridin-3(2H)-one monohydrate
Huichun Zhu,Michael B. Plewe,Arnold L. Rheingold,Curtis Moore
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536809053331
Abstract: rac-Benzyl 3-oxohexahydro-1H-pyrrolo[3,4-c]pyridine-5(6H)-carboxylate was separated by chiral chromatography, and one of the enantiomers ([α]22D = +10°) was hydrogenated in the presence of Pd/C in methanol, producing octahydro-3H-pyrrolo[3,4-c]pyridin-3-one. The latter was reacted with (2R)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoyl chloride [(R)-( )-Mosher acid chloride], giving rise to the title compound, C17H19F3N2O3·H2O. The present structure established the absolute configuration of the pyrrolopiperidine fragment based on the known configuration of the (R)-Mosher acid chloride. The piperidine ring has a somewhat distorted chair conformation and is cis-fused with the five-membered envelope-shaped ring; the plane of the exocyclic amide bond is approximately orthogonal to the plane of the phenyl ring, making a dihedral angle of 82.31 (3)°. The water molecule acts as an acceptor to the proton of the amino group in an N—H...O interaction, and as a double proton donor in O—H...O hydrogen bonds, generating infinite bands along the a axis.
5-Chloro-N-[2-(1H-imidazol-4-yl)ethyl]-N-methyl-7H-pyrrolo[2,3-d]pyrimidin-4-amine
Daniel Richter,John C. Kath,Arnold L. Rheingold,Antonio DiPasquale
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536809054750
Abstract: The title compound, C12H13ClN6, was prepared by reaction of 4,5-dichloro-7H-pyrrolo[2,3-d]pyrimidine with 2-(1H-imidazol-4-yl)-N-methylethanamine, and the X-ray study confirmed that chloro-substituent in six-membered ring was replaced in the reaction. The exocyclic N atom environment is approximately coplanar with the pyrrolo[2,3-d]pyrimidine [corresponding dihedral angle is 5.5 (1)°], whereas the mean plane of the N—C—C—C link connecting with the imidazolyl ring is almost exactly orthogonal to the plane of the bicyclic system [dihedral angle = 91.6 (2)°]. The imidazolyl plane itself, however, forms a relatively small dihedral angle of 20.8 (1)° with the pyrrolo[2,3-d]pyrimidine plane. There are two independent N—H...N hydrogen bonds in the structure, which link molecules into layers parallel to (overline{1}03).
N,N′-Dibenzyl-N′′-(2,6-difluorobenzoyl)-N,N′-dimethylphosphoric triamide
Mehrdad Pourayoubi,Atekeh Tarahhomi,Arnold L. Rheingold,James A. Golen
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810035725
Abstract: The phosphoryl and carbonyl groups in the title compound, C23H24F2N3O2P, are anti to each other. The P atom is in a tetrahedral coordination environment and the environment of each N atom is essentially planar, the average bond angles at the two N atoms being 119.9 and 119.1°. The H atom of the C(=O)NHP(=O) group is involved in an intermolecular –P=O...H–N– hydrogen bond, forming centrosymmetric dimers.
tert-Butyl 4-(1-methyl-1H-pyrazol-5-yl)piperidine-1-carboxylate
Daniel Richter,John C. Kath,Arnold L. Rheingold,Antonio DiPasquale
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809010332
Abstract: The reaction of (E)-tert-butyl 4-[3-(dimethylamino)acryloyl]piperidine-1-carboxylate with methylhydrazine leads to the formation of the title compound, C14H23N3O2, with a 1-methyl-1H-pyrazol-5-yl substituent. The plane of the pyrazole ring forms a dihedral angle of 33.4 (1)° with the approximate mirror plane of the piperidine ring.
N,N′-Di-tert-butyl-N′′-(2,6-difluorobenzoyl)phosphoric triamide
Mehrdad Pourayoubi,Atekeh Tarahhomi,Arnold L. Rheingold,James A. Golen
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810045927
Abstract: In the title compound, C15H24F2N3O2P, the phosphoryl and carbonyl groups adopt anti positions relative to each other. The P atom is in a tetrahedral coordination environment and the environment of each N atom is essentially planar. In the crystal, adjacent molecules are linked via N—H...O=P and N—H...O=C hydrogen bonds into an extended chain parallel to the a axis. The crystal studied was a non-merohedral twin with a minor twin component of 36.4 (1)%.
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