- Microwave Induced Synthesis of 3,4-Dihydro-2H-pyran-2-carboxaldehyde: A Versatile Linker for Solid Phase Combinatorial Library
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Procedures for the dimerization of acrolein to form 3,4-dihydro-2H-pyran-2-carboxaldehyde by microwave induced synthesis have been developed. Significant rate-enhancement and yield increase were observed. 3,4-Dihydro-2H-pyran-2-carboxaldehyde was obtained in 91% yield under microwave irradiation for 5 minutes instead of 39% yield by reacting at 190 °C for 40 min or at 160 °C for 4 hr.
- Hsieh, Hsing-Pang,Chen, Shui-Tein,Wang, Kung-Tsung
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- Substituents influences on the rate of α-alkylacroleins dimerization
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Kinetics of α-alkylacroleins dimerization was studied. It was established that both electronic and steric factors affect the process rate, with the prevalence of the latter factors.
- Karpyak,Makitra,Polyuzhin,Marshalok,Koval'Skii
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- Synthesis of 15N-labelled 3,5-dimethylpyridine
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15N-labelled pyridines are liquid- and solid-state nuclear magnetic resonance (NMR) probes for chemical and biological environments because their 15N chemical shifts are sensitive to hydrogen-bond and protonation states. By variation of the type and number of substituents, different target pyridines can be synthesized exhibiting different pKa values and molecular volumes. Various synthetic routes have been described in the literature, starting from different precursors or modification of other 15N-labelled pyridines. In this work, we have explored the synthesis of 15N 15N-labelled pyridines using a two-step process via the synthesis of alkoxy-3,4-dihydro-2H-pyran as precursor exhibiting already the desired pyridine substitution pattern. As an example, we have synthesized 3,5-dimethylpyridine-15N (lutidine-15N) as demonstrated by 15N-NMR spectroscopy. That synthesis starts from methacrolein, propenyl ether, and 15N-labelled NH4Cl as nitrogen source.
- Schubert, Mario,Limbach, Hans-Heinrich,Elguero, José
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- Lewis Acid-Catalyzed Synthesis of Benzofurans and 4,5,6,7-Tetrahydrobenzofurans from Acrolein Dimer and 1,3-Dicarbonyl Compounds
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2,3-Disubstituted benzofurans were synthesized from acrolein dimer and 1,3-dicarbonyl compounds by using N-bromosuccinimide as an oxidizing agent. The method was used to synthesize two commercial drug molecules, benzbromarone and amiodarone. The proposed mechanism of the reaction involves a N-bromosuccinimide (NBS)-assisted autotandem catalysis with Lewis acid catalyst. To proof the proposed mechanism, an intermediate was isolated successfully, which can be converted to 4,5,6,7-tetrahydrobenzofurans.
- Huang, Wenbo,Xu, Jing,Liu, Changhui,Chen, Zhiyan,Gu, Yanlong
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p. 2941 - 2950
(2019/02/26)
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- CCR2 MODULATORS
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Compounds are provided that are modulators of the CCR2 receptor. The compounds have the general formula (I) and are useful in pharmaceutical compositions, methods for the treatment of diseases and disorders involving the pathologic activtation of CCR2 receptors.
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Paragraph 0154; 0155
(2016/12/07)
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- Design, synthesis, in vitro cytotoxicity evaluation and structure-activity relationship of Goniothalamin analogs
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A series of six/five member (E/Z)-Goniothalamin analogs were synthesized from commercially available (3,4-dihydro-2H-pyran-2-yl)methanol/5- (hydroxymethyl)dihydrofuran-2(3H)-one in three steps with good to moderate overall yields and their cytotoxicity against lymphoblastic leukemic T cell line (Jurkat E6.1) have been evaluated. Among the synthesized analogs, (Z)-Goniothalamin appeared to be the most active in cytotoxicity (IC 50 = 12 μM). Structure-activity relationship study indicates that introducing substituent in phenyl ring or replacing phenyl ring by pyridine/naphthalene, or decreasing the ring size of lactones (from six to five member) do not increase the cytotoxicity.
- Mohideen, Mazlin,Zulkepli, Suraya,Nik-Salleh, Nik-Salmah,Zulkefeli, Mohd,Weber, Jean-Frédéric Faizal Abdullah,Rahman, A. F. M. Motiur
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p. 812 - 831
(2013/07/26)
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- Towards a library of chromene cannabinoids: A combinatorial approach on solid supports
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A novel solid-phase synthesis towards classical cannabinoids is presented. Starting from immobilized salicylaldehydes the desired THC-analogous tricycles are obtained in four atom-economic steps including cleavage. The reagents of the employed reactions (domino oxa-Michael-aldol, Wittig, and Diels-Alder) can be varied easily, providing the basis for a combinatorial approach. Overall yields range from 20-60%. Georg Thieme Verlag Stuttgart New York.
- Kapeller, Dagmar C.,Br?se, Stefan
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supporting information; experimental part
p. 161 - 164
(2011/03/19)
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- Recrossing and dynamic matching effects on selectivity in a diels-alder reaction
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Up and down the hill: The products from the hetero-Diels-Alder reaction of acrolein with methyl vinyl ketone arise from a single transition state (see scheme) and trajectory studies accurately predict the selectivity. In an extension of the dynamic matchi
- Wang, Zhihong,Hirschi, Jennifer S.,Singleton, Daniel A.
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supporting information; experimental part
p. 9156 - 9159
(2010/03/03)
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- Enantioconvergent synthesis by sequential asymmetric Horner-Wadsworth-Emmons and palladium-catalyzed allylic substitution reactions
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A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different α-oxygen-substituted, racemic aldehydes were initially transformed by asymmetric HWE reactions into mixtures of two major α,β-unsaturated esters, possessing opposite configurations at their allylic stereocenters as well as opposite alkene geometry. Subsequently, these isomeric mixtures of alkenes could be subjected to palladium-catalyzed allylic substitution reactions with carbon, nitrogen, and oxygen nucleophiles. In this latter step, the respective (E) and (Z) alkene substrate isomers were observed to react with opposite stereospecificity: the (E) alkene reacted with retention and the (Z) alkene with inversion of stereochemistry with respect to both the allylic stereocenter and the alkene geometry. Thus, a single γ-substituted ester was obtained as the overall product, in high isomeric purity. The method was applied to a synthesis of a subunit of the iejimalides, a group of cytotoxic macrolides.
- Pedersen,Hansen,Kane,Rein,Helquist,Norrby,Tanner
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p. 9738 - 9742
(2007/10/03)
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- Facile syntheses of 7,7-dimethyl-6,8-dioxabicyclo [3.2.1]octane, a constituent of the Japanese hop oil, and frontalin via hetero Diels-Alder reaction using dilution method
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A constituent of the Japanese hop oil, Humulus lupulus, and frontalin has been prepared as racemates in short and the most convenient pathway via hetero Diels-Alder reaction using dilution method.
- Jun, Jong-Gab,Lee, In-Suk
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p. 1159 - 1165
(2007/10/03)
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- Asymmetric Induction in the Wittig-Still Rearrangement of Ethers Containing an Allylic Stereocenter - Diastereocontrol by Allylic Oxygen
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Stannylated allyl ethers 13, 15, 19 and 21 bearing an allylic center of chirality are submitted to the Still variant of the Wittig rearrangement.In these reactions alkoxy groups at the chiral center exert stereocontrol through asymmetric induction.With only few exceptions , the syn-configurated rearrangement product (27) is formed in preference to the anti epimer (28), syn:anti ratios are often >90:98:3J between β- and γ-protons may be used to assign the stereochemistry in epimeric syn and anti γ-alkoxy alcohols.
- Priepke, Henning,Brueckner, Reinhard
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p. 153 - 168
(2007/10/02)
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- KINETICS AND MECHANISM OF CYCLODIMERIZATION OF α-SUBSTITUTED ACROLEINS
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The kinetics of the thermal cyclodimerization of α-alkoxyacroleins were investigated for the case of α-ethoxyacrolein in the range of 98-130 deg C in cyclohexane and at 115 deg C in various solvents.The rate constant for the cyclodimerization of α-ethoxyacrolein (8.29*10-4 liter/mole*sec at 130 deg C in benzene) is two orders of magnitude higher than the analogous constant for acrolein.The activation energy for the cyclodimerization of α-ethoxyacrolein is 86 kJ/mole, log A = 7.1.The rate constant does not depend on the polarity of the solvent or on the cationic catalyst (MoCl5).The regioselectivity of the cyclodimerization of acrolein and its α-alkoxy and α-alkylthio analogs and also the ratio of the rate constants are explained in terms of Hueckel perturbation theory (PMO).It is supposed that the thermal cyclodimerization of the investigated acroleins takes place by a nonsynchronous mechanism.The idea of a transition state involving the β-carbon atoms of two molecules of the monomer seems most probable.
- Keiko, N. A.,Stepanova, L. G.,Vainberg, N. N.,Bannikova, O. B.,Voronkov, M. G.
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p. 419 - 423
(2007/10/02)
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