- Rapid Fluorescent Screening for Bifunctional Amine-Acid Catalysts: Efficient Syntheses of Quaternary Carbon-Containing Aldols under Organocatalysis
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(Equation presented) Direct catalytic aldol reactions of α.α-dialkylaldehyde donors and arylaldehyde acceptors have been performed using pyrrolidine-acetic acid bifunctional catalysts. This general and practical amine-acid combination was identified by sc
- Mase, Nobuyuki,Tanaka, Fujie,Barbas III, Carlos F.
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Read Online
- Preparation method of trifluoromethyl substituted carboxylic acid compound
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The invention provides a preparation method of a trifluoromethyl substituted carboxylic acid compound. The method is significantly advantageous over processes in the prior art. Advantages are reflected in low cost and high yield. Another alternative schem
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Paragraph 0083; 0084; 0085
(2019/01/23)
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- Enamines as Surrogates of Alkyl Carbanions for the Direct Conversion of Secondary Amides to α-Branched Ketones
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A direct transformation of secondary amides into α-branched ketones with enamines as soft alkylation reagents was developed. In this reaction, enamines serve as surrogates of alkyl carbanions, rather than the conventional enolates equivalents in the Stork's reactions, which allowed for the easy introduction of alkyl groups with electrophilic functional groups. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot coupling of secondary amides with aldehydes to yield ketones. (Figure presented.).
- Liu, Yong-Peng,Wang, Shu-Ren,Chen, Ting-Ting,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
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supporting information
p. 971 - 975
(2019/01/25)
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- Cross-Coupling of Secondary Amides with Tertiary Amides: The Use of Tertiary Amides as Surrogates of Alkyl Carbanions for Ketone Synthesis
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In recent years, exciting progress has been made in the field of direct transformation of amides, nevertheless, the condensation between two amides remains rare and restricted to homo-coupling reactions. Herein, we report the cross-coupling of secondary amides with tertiary amides, which provides a synthesis of ketones under mild conditions, and features the use of tertiary amides as surrogates of alkyl carbanions. The method relies on the coupling of enamines, generated from tertiary amides by catalytic partial reduction of tertiary amides with Vaska's catalyst, with nitrilium ions, formed in situ from secondary amides via activation with trifluoromethanesulfonic anhydride, and on the subsequent deformylation.
- Wang, Shu-Ren,Huang, Pei-Qiang
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p. 887 - 891
(2019/07/18)
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- Facile Installation of 2-Reverse Prenyl Functionality into Indoles by a Tandem N-Alkylation-Aza-Cope Rearrangement Reaction and Its Application in Synthesis
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An unprecedented tandem N-alkylation-ionic aza-Cope (or Claisen) rearrangement-hydrolysis reaction of readily available indolyl bromides with enamines is described. Due to the complicated nature of the two processes, an operationally simple N-alkylation and subsequent microwave-irradiated ionic aza-Cope rearrangement-hydrolysis process has been uncovered. The tandem reaction serves as a powerful approach to the preparation of synthetically and biologically important, but challenging, 2-reverse quaternary-centered prenylated indoles with high efficiency. Notably, unusual nonaromatic 3-methylene-2,3-dihydro-1H-indole architectures, instead of aromatic indoles, are produced. Furthermore, the aza-Cope rearrangement reaction proceeds highly regioselectively to give the quaternary-centered reverse prenyl functionality, which often produces a mixture of two regioisomers by reported methods. The synthetic value of the resulting nonaromatic 3-methylene-2,3-dihydro-1Hindole architectures has been demonstrated as versatile building blocks in the efficient synthesis of structurally diverse 2-reverse prenylated indoles, such as indolines, indolefused sultams and lactams, and the natural product bruceolline D.
- Chen, Xiaobei,Fan, Huaqiang,Zhang, Shilei,Yu, Chenguang,Wang, Wei
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supporting information
p. 716 - 723
(2016/01/12)
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- Rhodium(III)/Amine Synergistically Catalyzed Enantioselective Alkylation of Aldehydes with α,β-Unsaturated 2-Acyl Imidazoles
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A synergistic catalysis combination of chiral-at-metal rhodium complex and amine catalyst was developed for enantioselective alkylation of aldehydes with α,β-unsaturated 2-acyl imidazoles. The corresponding adducts were obtained in good yields with excellent enantioselectivities (up to 99% ee).
- Gong, Jun,Li, Kuan,Qurban, Saira,Kang, Qiang
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supporting information
p. 1225 - 1235
(2016/12/28)
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- Visible light induced photocatalytic conversion of enamines into amides
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A series of enamines were photocatalytically cleaved to produce amide products under simple visible-light irradiation from a 45 W household light bulb. Mechanistically, the reactions appear to involve photosensitized formation of a singlet oxygen intermediate and a subsequent [2+2] cycloaddition event. Georg Thieme Verlag Stuttgart, New York.
- Li, Jing,Cai, Shunyou,Chen, Jietao,Zhao, Yaohong,Wang, David Zhigang
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supporting information
p. 1626 - 1628
(2014/07/08)
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- Azepanone-based inhibitors of human cathepsin S: Optimization of selectivity via the P2 substituent
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A series of azepanone inhibitors of cathepsin S is described. Selectivity over both cathepsin K and cathepsin L was achieved by varying the P2 substituent. Ultimately, a balanced potency and selectivity profile was achieved in compound 39 possessing a 1-methylcyclohexyl alanine at P2 and nicotinamide as the P′ substituent. The cellular potency of selected analogs is also described.
- Kerns, Jeffrey K.,Nie, Hong,Bondinell, William,Widdowson, Katherine L.,Yamashita, Dennis S.,Rahman, Attiq,Podolin, Patricia L.,Carpenter, Donald C.,Jin, Qi,Riflade, Benoit,Dong, Xiaoyang,Nevins, Neysa,Keller, Paul M.,Mitchell, Laura,Tomaszek, Thaddeus
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scheme or table
p. 4409 - 4415
(2011/09/15)
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- Synthesis of 6 H-dibenzo[ b, d ]pyran-6-ones using the inverse electron demand Diels-Alder reaction
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A set of coumarin-fused electron-deficient 1,3-dienes was synthesized, which differ in the nature of the electron-withdrawing group (EWG) at the terminus of the diene unit and (when EWG = CO2Me) the nature and position of substituents. These dienes reacted with the enamine derived from cyclopentanone and pyrrolidine to afford the corresponding cyclopenteno-fused 6H-dibenzo[b,d]pyran-6-ones, most likely via a domino inverse electron demand Diels-Alder (IEDDA)/elimination/transfer hydrogenation sequence. The parent diene (EWG = CO2Me, no substituents) was reacted with a range of electron-rich dienophiles (mostly enamines) to afford the corresponding 6H-dibenzo[b,d]pyran-6-ones or their nondehydrogenated precursors, which were aromatized upon treatment with a suitable oxidant. The enamines could either be synthesized prior to the reaction or generated in situ. The syntheses of 30 dibenzopyranones are reported.
- Pottie, Ian R.,Nandaluru, Penchal Reddy,Benoit, Wendy L.,Miller, David O.,Dawe, Louise N.,Bodwell, Graham J.
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experimental part
p. 9015 - 9030
(2011/12/03)
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- Ring-closing metathesis of allylsilanes as a flexible strategy toward cyclic terpenes. Short syntheses of teucladiol, isoteucladiol, poitediol, and dactylol and an attempted synthesis of caryophyllene
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The development of a strategy consisting of allylsilane ring-closing metathesis and subsequent SE′ electrophilic desilylation (allylsilane RCM/SE′) to construct exo-methylidenecycloalkanes is described. Its utility is documented in short syntheses of teucladiol and poitediol. A key transformation in the synthesis of teucladiol is an aldol addition that establishes three stereochemical relationships in one step with ≥10:1 diastereoselectivity and provides a fascinating example of double stereodifferentiation/kinetic resolution with racemic reaction partners in the context of natural product synthesis. The synthesis of (±)-teucladiol required five steps from cyclopentenone and proceeded in 28% overall yield; adaptation of this route to an enantioselective synthesis of (-)-teucladiol enabled the determination of the absolute configuration of this terpene natural product. The use of fluoride-mediated conditions in the final desilylation step preserves the location of the alkene, delivering the natural product (±)-isoteucladiol (five steps and 21% yield from cyclopentenone). The synthesis of poitediol showcases the power of RCM for constructing eight-membered rings and features a highly diastereoselective epoxidation/fluoride-mediated fragmentation sequence for installing the exo-methylidene group with an adjacent hydroxyl-bearing stereocenter. The synthesis of (±)-poitediol required seven steps and proceeded in 18% overall yield. Again, fluoride-mediated desilylation of a late-stage intermediate (with retention of double-bond location) delivered the natural product (±)-dactylol (seven steps and 24% yield). Efforts directed toward incorporating the RCM/SE′ sequence into a synthesis of caryophyllene are also disclosed. While ultimately unsuccessful, these efforts resulted in the identification of a novel metal alkylidene-promoted deallylation reaction of terminal 1,4-dienes. A possible mechanism for this unexpected deallylation reaction of 1,4-dienes is provided.
- Dowling, Matthew S.,Vanderwal, Christopher D.
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experimental part
p. 6908 - 6922
(2010/11/24)
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- Improved Titanium Tetrachloride Procedure for Enamine Synthesis.II.Scope of the Reaction
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The scope of enamine formation by a procedure where the carbonyl compound is added to a preformed titanium tetrachloride-amine complex was investigated with a series of different types of carbonyl compounds and two secondary amines (morpholine and pyrrolidine).The carbonyl compounds include aldehydes, cyclic ketones and some substituted aryl alkyl ketones.Yields of isolated products were in the range 67-100 percent with the exception of the pyrrolidine enamine from camphor which gave 53 percent of the isolated product.
- Carlson, Rolf,Nilsson, Asa
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- Synthesis of α-Cyanoenamines by Cyanation of α-Bromoimmonium Bromides and Dehydrobromination of β-Bromo-α-(dialkylamino)nitriles
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The reaction of α-bromoimmonium bromides 4 with potassium cyanide in dimethylformamide gave rise to β-bromo-α-(dialkylamino)nitriles 5, which were dehydrobrominated in various base solvent systems to afford (E)- and (Z)-α-cyanoenamines 2.An adaption of a previously published preparation of α-cyanoenamines starting from aldehydes via enamines led to an improved, efficient and fast synthesis of the title compounds.
- Kimpe, Norbert De,Verhe', Roland,Buyck, Laurent De,Schamp, Niceas
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p. 3846 - 3857
(2007/10/02)
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- Alkyl Substituent Effects on the Photorearrangement of Cyclohex-2-en-1-ones to Lumiketones
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The effect of alkyl substitution on the photorearrangement of cyclohex-2-en-1-ones to bicyclohexan-2-ones (lumiketones) was investigated.Contrary to earlier reports, both 2,4,4- and 3,4,4-trimethylcyclohex-2-en-1-one undergo this rearrangement upon
- Schuster, David I.,Rao, Jampani Madhusudana
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p. 1515 - 1521
(2007/10/02)
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