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The structure of dirhodium compounds contains a unique Rh-Rh bond, two axial ligands and four bridging ligands. In the dirhodium(II) compounds, it is easy to migrate the coordinating atoms of the bridging ligand during the catalysis process, which leads to the degradation of the catalyst. Coordination atom migration was identified in bridging ligands. To improve the catalyst stability, we carried out a study on the effect of fine-tuning of the bridging ligand on the dirhodium compound. Several dirhodium compounds were designed and synthesized. During this process, we have successfully found Rh2(5-Br-esp)2 and Rh2(5-tBu-esp)2, which are closer to the ideal geometric configuration of the dirhodium(II) compounds. Rh2(5-Br-esp)2 has been applied in the oxidation of propargyl position and Rh2(5-tBu-esp)2 in the formation reaction of the C–N bond.

A Ca(OTf)2- and self-promoted ynone-amidine atom-economic formal [4 + 2]-cycloaddition of various ynones with amidines is reported for the construction of highly functionalized tricyclic azepines. High reaction rate, ease of operation, and high product se

The first general method for the synthesis of α-alkyl ynones was developed based on the strategy of electrophilic activation of amides. Its distinctive advantages are attributed to the use of air-stable "bare"1-copper(I) alkyne as a mild nucleophile witho

In this study, we developed a convenient and efficient two-step method for the synthesis of ynones in a flow reactor, through the generation of lithium acetylide and its subsequent reactions with acid chlorides. Using this approach, we obtained the ynones in moderate to good yields at room temperature. Moreover, we transformed the ynones into pyrazole derivatives through coupling with hydrazines. This transition metal-free process, mild reaction conditions, and broad functional group tolerance are all attractive features in comparison with conventional bench-top methods.

Investigation of the copper-catalyzed coupling reaction of 2-pyridinesulfonates with Grignard reagents revealed that reactions with catalytic Cu(OTf)2 were completed in 40 min. The results differed from those of the previous CuI-catalyzed reactions of tosylates in the presence of additives (LiOMe and TMEDA) for 12-24 h. It was shown that the preferred coordination of the leaving group to the reagents accelerated the reaction. Successful reagents were MeMgCl and other RMgX. Complete inversion was established.

A highly atom-economical protocol for the synthesis of tetrasubstituted furans has been developed. This process is realized through the tandem reactions of Cs2CO3 promoted C-C σ-bond activation of α-aryl ketones followed by Zn-cataly

A phosphine-catalyzed intermolecular annulation reaction of functionalized ortho-aminoacetophenones with alkynones has been disclosed in this paper. A variety of 2-alkynylquinolines and benzo-fused indolizine were selectively afforded in moderate to good yields at different reaction temperatures and with different phosphine catalysts via the in situ generated zwitterionic intermediate derived from alkynone and phosphine. (Figure presented.).

A novel photoredox catalysis for multiple functionalization of two different types of unactivated alkenes in a single operation was reported through a conceptually new mode of annulation-alkynyl migration. A wide array of cyclopentane carboxylates were sy

We describe herein a fundamentally new visible light-driven homolytic C-C bond breaking mode for the generation of acyl radicals from C2-acyl-substituted benzothiazolines. The reactive species can be used as versatile synthons for formal radical alkylatio

The oxidation of alkynes to α,β-acetylenic carbonyls was achieved using only 1 mol% of a Cu(II) 2-quinoxalinol salen catalyst with tert-butyl hydroperoxide. These reactions proceed under mild conditions (70 °C) with excellent selectivity, producing yields up to 78%, and were used on a variety of alkyne substrates to produce the desired corresponding α,β-acetylenic ketones. In addition, these reactions can be run under aqueous conditions using a sulfonated version of the 2-quinoxalinol salen with good yields, reducing the need for volatile organic solvents.

A new combination of "anti-Baldwin" 3-exo-dig cyclization with 1,2-alkynyl migration of 1,4-enynes with simple cycloalkanes was established, enabling C-C breaking and reconstruction to access a wide range of α-alkynyl ketones with generally good yields by

Two regioselective synthetic routes towards 3,5-disubstituted isoxazoles from ynones are reported. One route takes place via first converting the ynones to ynone O-methyl oximes, followed by a palladium-catalyzed intramolecular cyclization. The other invo

A practical and efficient catalyst system for the oxidation of alcohols to carbonyl compounds using catalytic amounts of DDQ and Fe(NO3)3 with air as the environmentally benign oxidant has been developed. A variety of benzylic, heterocyclic, allylic and propargylic alcohols were smoothly converted into aldehydes or ketones in good to excellent yields. In case of large-scale reaction for the oxidation of benzyl alcohol, benzaldehyde was obtained in 93% isolated yield. Moreover, a possible reaction mechanism was proposed.

A general and efficient biogenic CuFe2O4 MNP's catalyzed synthesis of ynones has been reported for the first time. The reaction occurs in solvent free conditions without the use of any harsh conditions. The average diameter of the na

New pyrido[2,3-d]pyrimidines 11, 12, 13, and 21 have been synthesized. The vasorelaxant effect on smooth muscle isolated from rat aorta, via PDEs inhibition, of these compounds along with other pyrido[2,3-d]pyrimidines 14, 15, 16, 17, 18, 19, 20 reported earlier by our group, has also been determined. These pyrido[2,3-d]pyrimidines 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 were synthesized by the reaction of ferrocenyl-ethynyl ketones (1, 2, 3, 4) or α-alkynyl ketones (5, 6, 7, 8, 9, 10) with 6-amino-1,3-dimethyluracil using [Ni(CN)4]?4as an active catalytic species, formed in situ in a Ni(CN)2/NaOH/H2O/CO/KCN aqueous system. Evaluation of the vasorelaxant effect of compounds 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 demonstrated that all compounds relax the tissue in a concentration-dependent manner. The structural changes do not alter the effectiveness; however, there are differences related to potency expressed as EC50. Compounds 12 (7-ferrocenyl-1,3-dimethyl-5-(m-tolyl)-pyrido[2,3-d]pyrimidine) and 13 (7-ferrocenyl-1,3-dipropyl-5-(4-metoxyphenyl)-pyrido[2,3-d]pyrimidine) were the most potent compounds, even more than rolipram, reference drug; the EC50was 0.41 ± 0.02 μM and 0.81 ± 0.11 μM for 12 and 13, correspondingly. The EC50of compounds 15 (7-ferrocenyl-1,3-dimethyl-5-phenyl-pyrido[2,3-d]pyrimidine), 14 (7-ferrocenyl-5-(3,5-dimethoxyphenyl)-1,3-dimethylpyrido[2,3-d]pyrimidine), and 19 (5-n-butyl-7-ethyl-1,3-dimethylpyrido[2,3-d]pyrimidine) was similar to EC50of rolipram. Compounds 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 significantly induce concentration-dependent vasorelaxation in endothelium-intact aortic rings. In addition, the relaxation responses to each compound in either endothelium-intact or endothelium denuded aortic rings were comparable, suggesting that removal of the functional endothelium has no significant influence on its intrinsic vasorelaxant activity. In vitro capability of conserving cyclic-AMP or cyclic-GMP (adenosine and guanosine 3′, 5′-cyclic monophosphate) via PDE inhibition for compounds 12, 13, 14, 15 and 19 was evaluated. Compounds 15 and 19 show the highest percent inhibition effect (94.83% and 83.98%, respectively) for the decomposition of c-AMP. Docking studies showed that the compound 15 was selective for the inhibition of PDE-4.

We show that the dirhodium(II) tetraamidinate complex Rh2(Msip)4 efficiently catalyzes the oxidation of activated secondary alcohols at only 0.1 mol% loading. In this approach, we oxidized various benzylic, allylic and propargylic alcohols to the corresponding carbonyl compounds under mild aqueous conditions using the inexpensive oxidant T-HYDRO (70 wt% aqueous tert-butyl hydroperoxide).

A practical and efficient alternative version of the Swern oxidation has been successfully developed. Methyltrichlorosilane was used as an efficient activator of dimethylsulfoxide, which could oxidize a wide range of primary and secondary alcohols to the corresponding carbonyl compounds with good to excellent yields.

We found that the combination of [Ir(cod)Cl]2 and rac-BINAP served as an efficient catalyst for the [2+2+2] cycloaddition of 2,7-nonadiyne derivatives and related compounds with alkynyl ketones and alkynyl esters. The corresponding products wer

A mild and operationally simple procedure by Pd-catalyzed cross-coupling of acyl chlorides with in situ-generated alkynylzinc derivatives was developed, giving the corresponding ynones in good yields. Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications full experimental and spectral details.

An efficient and operationally simple procedure using Pd/BaSO 4-catalyzed cross coupling of acyl chlorides with in situ generated alkynylzinc derivatives was developed, giving the corresponding ynones at yields of 50%-96%.

The copper(II) complex of 2-quinoxalinol salen (salqu) is an efficient catalyst for the selective oxidation of propargylic alcohols to yield the corresponding α,β-acetylenic carbonyl compounds when used in combination with the oxidant tert-butyl hydroperoxide (TBHP). Excellent yields (up to 99 %) are achieved for a variety of propargylic alcohols within 1 h of reaction time. The (salqu)copper(II) complex with TBHP can be used with propargylic alcohols that contain alkyl groups in the α-position, which can be difficult to oxidize selectively with other commonly available methods. By using this catalytic protocol, excellent selectivity was also achieved for the oxidation of propargylic alcohols over that of isolated hydroxy groups, triple bonds, or propargylic methylene groups. The 2-quinoxalinol salen copper(II) complex is an efficient catalyst when used with tert-butyl hydroperoxide for the oxidation of propargylic alcohols to yield the corresponding carbonyl compounds. This catalytic system provides excellent selectivity for the reaction with propargylic alcohols, and high yields (up to 99 %) are achieved within 1 h and with 1 mol-% of catalyst loading. Copyright

Disclosed are compounds of Formula (I) [INSERT CHEMICAL STRUCTURE HERE] (I) or pharmaceutically acceptable salts thereof, wherein Q is [INSERT CHEMICAL STRUCTURE HERE] or [INSERT CHEMICAL STRUCTURE HERE]; R1 is alkyl or aryl, said aryl optionally substituted with one to five substituents independently selected from C1 to C6 alkyl, C1 to C4 haloalkyl, OR4, and/or halogen; and R2, R3, R4, and n are defined herein. Also disclosed are methods of using such compounds as selective agonists for G protein-coupled receptor S1P1, and pharmaceutical compositions comprising such compounds. These compounds are useful in treating, preventing, or slowing the progression of diseases or disorders in a variety of therapeutic areas, such as autoimmune diseases and vascular disease.

(Chemical Equation Presented) The trans-selective hydrosilylation of ynones (1) yields ss-silylated enones (2) that undergo a benzylic 1,4-rearrangement/cyclization reaction in the presence of base, yielding 2,5-dihydro-1,2-oxasiloles (3).

The photochemically initiated dehydro-Diels-Alder (PDDA) reaction is an efficient and versatile method for the preparation of biaryls. The ring closure may take place both inter- and intramolecularly, of which the intramolecular variant is more productive

Extremely efficient and high-speed ethynylation of acyl chlorides, aryl iodides and bromides was demonstrated by palladium-catalyzed cross-coupling reaction of N-t-butyl-Sb-ethynyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azastibocine under mild conditions. Optimization and generalization of the hypervalent antimony-mediated coupling reaction are presented in detail. Single-crystal X-ray analysis of the N-methyl-1,5-azastibocine revealed that the remarkable reactivity enhancement of the azastibocine was derived from elongation of the antimony-ethynyl carbon bond originated from Sb-N intramolecular non-bonding interaction.

The catalytic system composed of CuCl2 and 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt (BQC) was found to be highly efficient for the selective α-oxidation of internal alkynes to the corresponding α,β-acetylenic ketones, with aqueous tert-butyl hydroperoxide under mild conditions. For the first time, full conversions of alkynes were reached with excellent selectivities, and propargylic tert-butylperoxy ethers were observed and suggested as the reaction intermediates. In the case of terminal alkynes, the oxidations are sluggish and low yields ranging from 32% to 40% were obtained.

Simple organometallic cluster analogues of tamoxifen containing triosmium or dicobalt carbonyl fragments have been prepared. Attempts at elaboration of these towards the tamoxifen skeleton were hampered by sensitivity of the cluster-ligand linkage towards

The photo-dehydro-Diels-Alder reaction (PDDA), a new photochemical route to naphthalenes is presented. The [4+2] cycloaddition takes place between 3-arylynones and arylacetylenes. in which these moieties may be located in two molecules (intermolecular PDD

α,β-Acetylenic ketones were synthesized from the reaction of acid chlorides and acetylenic compounds in the presence of ZnBr2 and DIEA in acetonitrile. From the acetylenic ketones having nearby methylene unit, 2,5-disubstituted furan derivatives could be synthesized under the same reaction conditions.

The reaction of 12-arylethynyl-6-methyl-5,6,7,12-tetrahydrodibenzo[c,f][1, 5]-azastibocines with organic halides such as acyl halides and aryl halides in the presence of PdCl2(PPh3)2 as a catalyst led to the formation of cross-coupling products, alkynyl ketones and diaryl acetylenes, in good yields. The reactivity of the ethynyl group on the 1,5-azastibocines was far superior to that on diphenyl(phenylethynyl)stibane, which brought about marked improvement in the reaction conditions (lower temperature and shorter reaction time) and in the yields of the cross-coupling products. Single-crystal X-ray analysis of the ethynyl-1,5-azastibocine showed the presence of intramolecular Sb?N interaction which should be responsible for the remarkable reactivity enhancement of the 1,5-azastibocines for this type of reaction.

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Three novel polystyrene supported selenol esters were synthesized and used as acyl transfer agents to prepare α, β-acetylenic ketones by reaction with alkynylcoppers.

Reaction of alkynyltrichlorostannanes with carboxylic acid chlorides (anhydrides) was studied. The results obtained by varying substituents at the carbonyl group were used to propose a mechanism of the reaction, which was indirectly confirmed by further e

1-Alkynyldiphenylstibines react with acyl chlorides in dichloroethane in the presence of a palladium(0) or (II) catalyst to afford alkynyl ketones by cross-coupling reaction in good to moderate yields. These reactions are highly substituent-selective in that only the alkynyl group could be transferred from the antimony compounds, even in the presence of a large excess of acyl chlorides. (C) 2000 Elsevier Science Ltd.

Phenylacetylenic Grignard reagent reacts with acetic anhydride under mild conditions to give 4-phenyl-3-butyn-2-one in high yield. This method was applicable to a large-scale synthesis, and optimized reaction conditions have been investigated.

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1-(Benzotriazol-1-yl)propargyl ethyl ethers, readily accessible from propargyl aldehyde diethyl acetals and benzotriazole, undergo smooth lithiation at the methine carbon and subsequent reactions with alkyl halides, aldehydes, ketones, imines, esters, trialkylsilyl chlorides, dialkyl carbonates, and isocyanates to yield the corresponding substituted ethers.Hydrolysis of these intermediates under acidic conditions affords a wide variety of alkynyl ketones bearing hydroxy, amino, acyl, trimethylsilyl, alkoxycarbonyl, and (alkylamino)carbonyl substituents at the α-position in good to excellent overall yields.

The Midland reagent, Alpine-Borane (2a), is excellent for the asymmetric reduction of many acetylenic ketones but it fails with hindered derivatives.On the other hand, B-chlorodiisopinocampheylborane (DIP-Chloride, 4) reacts with hindered α,β-acetylenic k

α,α-Difluoroalkylamines, such as 1-diethylamino-2-chloro-1,1,2-trifluoroethane (1) and 1-diethylamino-1,1,2,3,3,3-hexafluoropropane (2), were found to be useful dehydrating agents for the sysnthesis of acetylenic ketones from β-diketones in the presence o