21539-55-9Relevant articles and documents
Effect of pressure on sterically hindered reactions with late transition states
Gacem, Badra,Jenner, Gerard
, p. 221 - 225 (2004)
The effect of high pressure is examined in two types of sterically congested reactions presenting late transition states: isopolar Diels-Alder cycloadditions of isoprene and quinones of various steric environment and conjugate additions of tert-butylamine and acrylic compounds. In the Diels-Alder cycloadditions, pressure has no enhanced kinetic sensitivity in sterically demanding reactions compared with unhindered ones. This is due to the structural closeness of the transition state and product. At variance, in the conjugate addition of amines, the effect of pressure is magnified with increasing steric congestion at the reaction centres. This is ascribed to enhanced electrostriction with removal of steric hindrance to ionization. Copyright
Synthesis of new pyrrolo[3,4-b]indol-3-ones as latent substrates for pyrrolo[3,4-b]indoles
Saulnier, Mark G.,Schreiber, Steven M.,Cavanaugh, Kerri L.,Perni, Robert B.,Joyner, H. Howard,Gribble, Gordon W.
, p. 15 - 23 (2020/11/19)
We report the synthesis of new examples of the 1,4-dihydropyrrolo[3,4-b]indol-3(2H)-one ring system via Fischer indolization between the appropriate phenylhydrazines and pyrrolidine-2,3-diones. Lithiation at the C-1 position with lithium diisopropylamide following by quenching with iodomethane affords 1-methyl-1,4-dihydropyrrolo[3,4-b]indol-3(2H)-ones in excellent yield.
HISTAMINE H3 INVERSE AGONISTS AND ANTAGONISTS AND METHODS OF USE THEREOF
-
Page/Page column 107, (2010/08/18)
Provided herein are fused imidazolyl compounds, methods of synthesis, and methods of use thereof. The compounds provided herein are useful for the treatment, prevention, and/or management of various disorders, such as neurological disorders and metabolic disorders. Compounds provided herein inhibit the activity of histamine H3 receptors and modulate the release of various neurotransmitters, such as histamine, acetylcholine, norepinephrine, and dopamine (e.g. at the synapse). Pharmaceutical formulations containing the compounds and their methods of use are also provided herein.
Preparation and intramolecular [2+2]-photocycloaddition of 1,5-dihydropyrrol-2-ones and 5,6-dihydro-1H-pyridin-2-ones with C-, N-, and O-linked alkenyl side chains at the 4-position
Albrecht, Dominik,Basler, Birte,Bach, Thorsten
, p. 2345 - 2356 (2008/09/19)
(Chemical Equation Presented) The 1,5-dihydropyrrol-2-ones 2, 6, 9, and 11 were prepared from methyl tetramates (1a-c), N-Boc-protected tetramic acid (3), or N-Boc-protected tetramic acid bromide (7) in short reaction sequences and in very good overall yields. The homologous 5,6-dihydro-1H-pyridin-2-ones 16,18, 20, 21, 23, and 27 were prepared along analogous routes starting from piperidin-2,4-dione (19) or from its N-terf-butyl derivative 15. Optimized conditions for the [2+2]-photocycloaddition include the use of dichloromethane as the solvent and an irradiation with a mercury low-pressure lamp (λ = 254 nm). Upon applying these conditions at ambient temperature, the corresponding intramolecular photocycloaddition products 28-37 were obtained in good yields (52-79%) and with perfect diastereoselectivity. The constitution and configuration of the products was elucidated by NMR-spectroscopy. For the O-tethered substrates 2a and 20, a strong decrease of the photocycloaddition rate with temperature was observed. The effect was less pronounced for N- and C-tethered substrates 6, 9, 23, and 27. The use of a chiral complexing agent to achieve enantioselective reactions appears viable. Complexing agent (-)-38, however, is not suited because of its instability at λ = 254 nm.
AMIDOPYRAZOLE DERIVATIVE
-
Page/Page column 38-39, (2010/11/23)
A platelet coagulation inhibitor which inhibits neither COX-1 nor COX-2 is provided. The inhibitor is a compound represented by general formula (I): wherein Ar1 and Ar2 independently represent a 5- or 6-membered aromatic heterocyclic group optionally substituted with 1 to 3 substituents, or a phenyl group optionally substituted with 1 to 3 substituents; R1 represents a lower acyl group, carboxyl group, a lower alkoxycarbonyl group, a lower alkoxy group, a lower alkyl group optionally substituted with 1 or 2 substituents, a carbamoyl group optionally substituted with 1 or 2 substituents, an oxamoyl group optionally substituted with 1 or 2 substituents, an amino group optionally substituted with 1 or 2 substituents, a 4- to 7-membered alicyclic heterocyclic group optionally substituted with 1 or 2 substituents, a phenyl group optionally substituted with 1 to 3 substituents, or a 5- or 6-membered aromatic heterocyclic group optionally substituted with 1 to 3 substituents; and R2 represents hydrogen atom, a halogeno group, or the like.
Synthesis and structural characterization of zirconium complexes containing aminodiolate ligands and their use as Lewis acid catalysts
Shao, Pengcheng,Gendron, Roland A.L.,Berg, David J.
, p. 255 - 264 (2007/10/03)
A series of aminodiols RN(CH2CH2C(OH)R′2)2 (R, R′ = Me, Me 4; Me, Ph 5; tert-butyl, Me 6; tert-Bu, Ph 7; (S)-PhCH(Me), Me 8) were prepared by the Michael addition of a primary amine to methyl acrylate followed by reaction of the resulting aminodiester with excess methyl or phenyl lithium. Reaction of two equivalents of the aminodiols 4-8 with tetrabenzylzirconium afforded the zirconium bis(aminodiolates) 10-14 in excellent yield. Complex 11 (R, R′ = Me, Ph) adopts a cis, fac-octahedral geometry in solution and in the solid state. Complexes 10-14 are fluxional in solution by NMR spectroscopy: small substituents at nitrogen and large substituents at the alkoxide carbons slow the rate of exchange. The chiral complex 14 functions as a Lewis acid catalyst in the nitroaldol (Henry) reaction and the oxidation of geraniol by tert-butyl hydroperoxide with modest enantioselectivities (30 and 46% enantiomeric excess (ee), respectively).
