- Synthesis of Cyclopentenones through Rhodium-Catalyzed C-H Annulation of Acrylic Acids with Formaldehyde and Malonates
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An efficient rhodium-catalyzed protocol for the synthesis of cyclopentenones based on a three-component reaction of acrylic acids, formaldehyde, and malonates via vinylic C-H activation is reported. Exploratory studies showed that 5-alkylation of as-prepared cyclopentenones could be realized smoothly by the treatment of a variety of alkyl halides with a Na2CO3/MeOH solution. Excess formaldehyde and malonate led to a multicomponent reaction that afforded the multisubstituted cyclopentenones through a Michael addition.
- Yu, Shuling,Hong, Chao,Liu, Zhanxiang,Zhang, Yuhong
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supporting information
p. 5054 - 5059
(2021/07/20)
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- Iodonium Ylides as Carbene Precursors in Rh(III)-Catalyzed C-H Activation
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The rhodium(III)-catalyzed coupling of C-H substrates with iodonium ylides has been realized for the efficient synthesis of diverse cyclic skeletons, where the iodonium ylides have been identified as efficient and outstanding carbene precursors. The reaction systems are applicable to both sp2 and sp3 C-H substrates under mild and redox-neutral conditions. The catalyst loading can be as low as 0.5 mol % in a gram-scale reaction. Representative products exhibit cytotoxicity toward human cancer cells at nanomolar levels.
- Jiang, Yuqin,Li, Pengfei,Li, Xingwei,Liu, Bingxian,Zhao, Jie
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supporting information
p. 7475 - 7479
(2020/10/12)
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- Exploring the Promiscuous Enzymatic Activation of Unnatural Polyketide Extender Units in Vitro and in Vivo for Monensin Biosynthesis
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The incorporation of new-to-nature extender units into polyketide synthesis is an important source for diversity yet is restricted by limited availability of suitably activated building blocks in vivo. We here describe a straightforward workflow for the biogenic activation of commercially available new-to-nature extender units. Firstly, the substrate scope of a highly flexible malonyl co-enzyme A synthetase from Streptomyces cinnamonensis was characterized. The results were matched by in vivo experiments in which the said extender units were accepted by both the polyketide synthase and the accessory enzymes of the monensin biosynthetic pathway. The experiments gave rise to a series of predictable monensin derivatives by the exploitation of the innate substrate promiscuity of an acyltransferase and downstream enzyme functions.
- Grote, Marius,Schulz, Frank
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p. 1183 - 1189
(2019/03/11)
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- Computational and experimental studies on copper-mediated selective cascade C-H/N-H annulation of electron-deficient acrylamide with arynes
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An efficient and convenient copper-mediated method has been developed to achieve direct cascade C-H/N-H annulation to synthesize 2-quinolinones from electron-deficient acrylamides and arynes. This method highlights an emerging but simple strategy to transform inert C-H bonds into versatile functional groups in organic synthesis to provide a new method of synthesizing 2-quinolinones efficiently. Mechanistic investigations by experimental and density functional theory (DFT) studies suggest that an organometallic C-H activation via a Cu(iii) intermediate is likely to be involved in the reaction.
- Chen, Chao,Hao, Yu,Zhang, Ting-Yu,Pan, Jin-Long,Ding, Jun,Xiang, Heng-Ye,Wang, Man,Ding, Tong-Mei,Duan, Abing,Zhang, Shu-Yu
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supporting information
p. 755 - 758
(2019/01/21)
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- Ni-Catalyzed Enantioselective Reductive Diarylation of Activated Alkenes by Domino Cyclization/Cross-Coupling
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A Ni-catalyzed enantioselective reductive diarylation of activated alkenes by domino cyclizative/cross-coupling of two aryl bromides is developed. This reaction proceeds under very mild conditions and shows broad substrate scope, without requiring the use of preformed organometallic reagents. Moreover, this approach provides direct access to various bis-heterocycles bearing all-carbon quaternary centers in synthetically useful yields (up to 81%) with excellent enantioselectivity (>30 examples, 90-99% ee).
- Wang, Kuai,DIng, Zhengtian,Zhou, Zhijun,Kong, Wangqing
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supporting information
p. 12364 - 12368
(2018/10/05)
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- Bifunctional Iminophosphorane Catalyzed Enantioselective Sulfa-Michael Addition to Unactivated α-Substituted Acrylate Esters
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The highly enantioselective sulfa-Michael addition of alkyl thiols to unactivated α-substituted acrylate esters catalyzed by a bifunctional iminophosphorane organocatalyst under mild conditions is described. The strong Br?nsted basicity of the iminophosphorane moiety of the catalyst provides the necessary activation of the alkyl thiol pro-nucleophile, while the two tert-leucine residues flanking a central thiourea hydrogen-bond donor facilitate high enantiofacial selectivity in the protonation of the transient enolate intermediate. The reaction is broad in scope with respect to the alkyl thiol, the ester moiety, and the α-substituent of the α,β-unsaturated ester, affords sulfa-Michael adducts in excellent yields (up to >99%) and enantioselectivities (up to 96% ee), and is amenable to decagram scale-up using catalyst loadings as low as 0.05 mol %.
- Farley, Alistair J. M.,Sandford, Christopher,Dixon, Darren J.
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supporting information
p. 15992 - 15995
(2016/01/15)
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- PROCESS FOR PREPARING BETA- (FLUOROPHENYL) -PROPANOATE ESTER DERIVATIVES
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A process for preparing a compound of formula (I) comprising reacting a compound of formula (II) with a fluorinated boron species of formula (III) in the presence of: an alcohol; a rhodium (I) pre-catalyst species; a suitable ligand that binds to the rhodium (I) pre-catalyst species to form a catalyst complex; a base; and, a suitable solvent; the process being carried out at a temperature in the range 40 to 110oC. The compounds of formula (I) are useful in the preparation of pharmaceutically active compounds.
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Page/Page column 8-9
(2008/06/13)
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- Microwave assisted hydrolysis of Meldrum's acid derivatives and decarboxylation of derived malonic acids
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Microwave induced hydrolysis of alkyl Medrum's acids and decarboxylation of derived malonic acids using poly-4-vinylpyridine as a catalyst gives high yields of carboxylic acids in a short time.
- Helavi,Solabannavar,Desai,Mane
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p. 174 - 175
(2007/10/03)
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- Antiretroviral hydrazine derivatives
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The invention relates to compounds of formula STR1 and salts, pharmaceutical compositions, intermediates and processes of preparation thereof.
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- Aminobenzoic and aminocyclohexanecarboylic acid compounds, compositions, and their method of use
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Compounds of the formula inhibit the action of neutral endopeptidase. As a result, such compounds produce diuresis, natriuresis, and lower blood pressure as well as being useful in the treatment of congestive heart failure, relieving pain, and diarrhea when administered to a mammalian host.
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- 1,1-Alkanediol dicarboxylate linked antibacterial agents
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Useful antibacterial agents in which a penicillin and/or a beta-lactamase inhibitor are linked via 1,1-alkanediol dicarboxylates are of the formula STR1 where A is the residue of certain dicarboxyic acids, R3 is H or (C1 -C3), n is zero or 1 such that when n is zero R is P or B and R1 is the residue of certain esters, H or a salt thereof; and when n is 1, one of R and R1 is P and the other is B, and P is STR2 where R2 is H or certain acyl groups, and B is the residue of a beta-lactamase inhibiting carboxylic acid; a method for their use, pharmaceutical compositions thereof and intermediates useful in their production.
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- Bis-esters of dicarboxylic acids with amoxicillin and certain hydroxymethylpenicillanate 1,1-dioxides
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Antibacterial bis-esters of 1,4-cyclohexanedicarboxylic acids and alkane dicarboxylic acids wherein the ester moieties are derived from different alcohols; one alcohol being hydroxymethylpenicillanate 1,1-dioxide, or the 6-beta-hydroxymethyl or the 6-alpha-aminomethyl derivative thereof; and the other being 6-[D-(2-amino-2-(p-hydroxyphenyl)acetamido)]penicillanic acid (amoxicillin); and pharmaceutically acceptable salts thereof; a method for the use of said esters and their salts, and methods for their preparation.
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