- Enantio- And Diastereodivergent Construction of 1,3-Nonadjacent Stereocenters Bearing Axial and Central Chirality through Synergistic Pd/Cu Catalysis
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In contrast to the widely explored methods for the asymmetric synthesis of molecules bearing a single stereocenter or adjacent stereocenters, the concurrent construction of 1,3-stereogenic centers in an enantio- and diastereoselective manner remains a challenge, especially in acyclic systems. Herein, we report an enantio- and diastereodivergent construction of 1,3-nonadjacent stereocenters bearing allenyl axial and central chirality through synergistic Pd/Cu-catalyzed dynamic kinetic asymmetric allenylation with racemic allenylic esters. The protocol is suitable for a wide range of substrates including the challenging allenylic esters with less sterically bulky substituents and provided chiral allenylic products bearing 1,3-nonadjacent stereocenters with high levels of enantio- and diastereoselectivities (up to >20:1 dr and >99% ee). Furthermore, several representative transformations involving axial-to-central chirality transfer were conducted, affording useful structural motifs containing nonadjacent stereocenters in a diastereodivergent manner.
- Huo, Xiaohong,Ma, Shengming,Xiao, Junzhe,Zhang, Jiacheng,Zhang, Wanbin,Zhao, Ling
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supporting information
p. 12622 - 12632
(2021/08/31)
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- ETHERS AND ESTERS OF TERTIARY ALKANOLS FOR USE AS AROMA CHEMICALS
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The present invention relates to the use of an ether or an ester of a tertiary alkanol or of mixtures of two or more ethers or esters of tertiary alkanols or of a stereoisomer thereof or of a mixture of two or more stereoisomers thereof as aromachemicals; to the use thereof for modifying the scent character of a fragranced composition; to an aroma chemical composition containing an ether or an ester of tertiary alkanol or of mixtures of two or more ethers or esters of tertiary alkanols or of a stereoisomer thereof or of a mixture of two or more stereoisomers thereof; and to a method of preparing a fragranced composition or for modifying the scent character of a fragranced composition. The invention further relates to specific ethers or esters of tertiary alkanols.
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Page/Page column 49; 50
(2020/05/21)
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- Base-Catalyzed Borylation/B-O Elimination of Propynols and B2pin2 Delivering Tetrasubstituted Alkenylboronates
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An efficient approach to tetrasubstituted alkenylboronates via a cascade borylation/B-O elimination of propynols and B2pin2 was disclosed. A series of tetrasubstituted alkenylboronates were readily furnished with this strategy in good yields, with further transformations leading to tetrasubstituted alkenes and β-diketones demonstrating the synthetic potential of the alkenylboronates constructed by this strategy as versatile intermediates in organic synthesis.
- Kuang, Zhijie,Chen, Haohua,Yan, Jianxiang,Yang, Kai,Lan, Yu,Song, Qiuling
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supporting information
p. 5153 - 5157
(2018/09/12)
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- Palladium(II)-Catalyzed Site-Selective C(sp3)?H Alkynylation of Oligopeptides: A Linchpin Approach for Oligopeptide–Drug Conjugation
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The palladium(II)-catalyzed C(sp3)?H alkynylation of oligopeptides was developed with tetrabutylammonium acetate as a key additive. Through molecular design, the acetylene motif served as a linchpin to introduce a broad range of carbonyl-containing pharmacophores onto oligopeptides, thus providing a chemical tool for the synthesis and modification of novel oligopeptide–pharmacophore conjugates by C?H functionalization. Dipeptide conjugates with coprostanol and estradiol were synthesized by this method for potential application in targeted drug delivery to tumor cells with overexpressed nuclear hormone receptors.
- Liu, Tao,Qiao, Jennifer X.,Poss, Michael A.,Yu, Jin-Quan
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supporting information
p. 10924 - 10927
(2017/08/30)
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- Fluoride-assisted activation of calcium carbide: A simple method for the ethynylation of aldehydes and ketones
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The fluoride-assisted ethynylation of ketones and aldehydes is described using commercially available calcium carbide with typically 5 mol % of TBAF·3H2O as the catalyst in DMSO. Activation of calcium carbide by fluoride is thought to generate an acetylide "ate"-complex that readily adds to carbonyl groups. Aliphatic aldehydes and ketones generally provide high yields, whereas aromatic carbonyls afford propargylic alcohols with moderate to good yields. The use of calcium carbide as a safe acetylide ion source along with economic amounts of TBAF·3H2O make this procedure a cheap and operationally simple method for the preparation of propargylic alcohols.
- Hosseini, Abolfazl,Seidel, Daniel,Miska, Andreas,Schreiner, Peter R.
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supporting information
p. 2808 - 2811
(2015/06/16)
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- Pd(II)-catalyzed highly regio-and stereoselective assembly of C-C double bonds: An efficient method for the synthesis of 2,4-dihalo-1,3,5-trienes from alkynols
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A highly efficient method for the synthesis of 2,4-dihalo-1,3,5-trienes from alkynols was developed. This chemistry allows access to multiple conjugated double bonds in a single step with high stereoselectivity.
- Jiang, Huanfeng,Gao, Yang,Wu, Wanqing,Huang, Yubing
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supporting information
p. 238 - 241
(2013/03/13)
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- BISPHENYL COMPOUNDS USEFUL AS VITAMIN D3 RECEPTOR AGONISTS
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The present invention discloses bisphenyl compounds of the formula (I): wherein R1, R2, R3, R4, R5, R6, X, Y, W are defined herein after. These compounds are useful as pharmaceuticals.
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Page/Page column 283-284
(2010/02/14)
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- Synthesis of alkyne derivatives of a novel triazolopyrazine as A 2A adenosine receptor antagonists
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A novel [1,2,4]triazolo[1,5-a]pyrazine core was synthesized and coupled with terminal acetylenes. The structure-activity relationship of the alkynes from this novel template was studied for their in vitro and in vivo adenosine A2A receptor antagonism. Selected compounds from this series were shown to have potent in vitro and in vivo activities against adenosine A 2A receptor. Compound 12, in particular, was found to be orally active at 3 mg/kg in both a mouse catalepsy model and a 6-hydroxydopamine- lesioned rat model.
- Yao, Gang,Haque, Serajul,Sha, Li,Kumaravel, Gnanasambandam,Wang, Joy,Engber, Thomas M.,Whalley, Eric T.,Conlon, Patrick R.,Chang, Hexi,Kiesman, William F.,Petter, Russell C.
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p. 511 - 515
(2007/10/03)
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- INDOLE-DERIVATIVE MODULATORS OF STEROID HORMONE NUCLEAR RECEPTORS
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The present invention provides a compound of formula I or a pharmaceutically acceptable salt thereof, pharmaceutical compositions comprising an effective amount of a compound of Formula I in combination with a suitable carrier, diluent, or excipient, and methods for treating physiological disorders, particularly congestive heart disease, comprising administering to a patient in thereof an effective amount of a compound of Formula I.
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- Anti-AIDS agents. Part 62: Anti-HIV activity of 2′-substituted 4-methyl-3′,4′-di-O-(-)-camphanoyl-(+)-cis-khellactone (4-methyl DCK) analogs
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Four 4-methyl-3′,4′-di-O-(-)-camphanoyl-(+)-cis-khellactone (4-methyl DCK) analogs (7a-d) with different alkyl substituents at the 2′-position were synthesized and evaluated for inhibition of HIV-1 replication in H9 lymphocytes. 2′-Methyl-2′-ethyl-4-methyl DCK (7b) was more potent (EC50 = 0.22 μM, TI > 175) than the other three compounds (7a, 7c, and 7d), but significantly less potent than 4-methyl DCK (2, EC50 = 0.0059 μM, TI > 6600). Four 4-methyl-3′,4′- di-O-(-)-camphanoyl-(+)-cis-khellactone (4-methyl DCK) analogs (7a-d) with different alkyl substituents at the 2′-position were synthesized and evaluated for inhibition of HIV-1 replication in H9 lymphocytes. 2′-Methyl-2′-ethyl-4-methyl DCK (7b) was more potent (EC 50 = 0.22 μM, TI > 175) than the other three compounds (7a, 7c, and 7d), but significantly less potent than 4-methyl DCK (2, EC50 = 0.0059 μM, TI > 6600). The bioassay results indicated that the 2′-substituents had a strong effect on the anti-HIV activity, and gem-dimethyl substitution at the 2′-position was greatly preferable to larger alkyl substituents or hydrogen atoms.
- Zhang, Qian,Chen, Ying,Xia, Peng,Xia, Yi,Yang, Zheng-Yu,Yu, Donglei,Morris-Natschke, Susan L.,Lee, Kuo-Hsiung
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p. 5855 - 5857
(2007/10/03)
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- The reaction of some propargyl alcohols with benzeneselenenyl chloride
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The reaction of benzeneselenenyl chloride with twenty-two propargyl alcohols in methylene chloride solution is reported.Products of both Markownikoff and anti-Markownikoff regiochemistry are formed in an anti stereospecific manner.The regioselectivity or specificity is found to be very dependent upon the nature of the substituents geminal to the alcoholic moiety.In general the presence of bulky substituents geminal to the alcoholic moiety tend to favour formation of the anti-Markownikoff adduct under conditions of kinetic control.The Markownikoff adducts are found to be favoured thermodynamically.
- Garratt, Dennis G.,Beaulieu, Pierre L.,Morisset, Veronique M.
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p. 927 - 934
(2007/10/02)
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- Preparation of a Series of Highly Hindered Secondary Amines, Including Bis(triethylcarbinyl)amine
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A series of highly branched secondary amines was prepared by coupling propargylamines with propargyl chlorides.Hydrogenation of the resultant dipropargylamines was accomplished with Raney nickel in the presence of potassium hydroxide.The resultant amines, including bis(triethylcarbinyl)amine, are among the most hindered secondary amines reported to date.The pKa values of the conjugate acids of the series of secondary amines exhibit a regular decrease with increasing size of the amine.The bulkier members of the series are inert to methyl iodide.Bis(triethylcarbinyl)amine reacts with boron trifluoride etherate to give a primary amine adduct and 3-ethyl-2-pentene.
- Kopka, Ihor E.,Fataftah, Zacharia A.,Rathke, Michael W.
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p. 4616 - 4622
(2007/10/02)
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