23350-58-5Relevant articles and documents
Total Synthesis of Strychnine
Lee, Geun Seok,Namkoong, Gil,Park, Jisook,Chen, David Y.-K.
, p. 16189 - 16193 (2017)
The total synthesis of the flagship Strychnos indole alkaloid, strychnine, has been accomplished. The developed synthetic sequence features a novel vinylogous 1,4-addition, a challenging iodinium salt mediated silyl enol ether arylation, a palladium-catalyzed Heck reaction, and a streamlined late-stage conversion to strychnine. Furthermore, an application of asymmetric counterion-directed catalysis (ACDC) in the context of target-oriented organic synthesis has been rendered access to an optically active material. The synthetic sequence described herein represents the most concise entry to optically active strychnine to date.
Convenient synthesis of various substituted homotaurines from alk-2-enamides
Nai, Youfeng,Xu, Jiaxi
, p. 1355 - 1365 (2013/08/23)
Various substituted homotaurines (=3-aminopropane-1-sulfonic acids) 6 were readily synthesized in satisfactory to good yields via the Michael addition of thioacetic acid to alk-2-enamides 3 (→4), followed by LiAlH4 reduction (→5) and performic acid oxidation (Scheme 1). The configuration of 'anti'-disubstituted homotaurine 'anti'-6h was deduced from the 3-(acetylthio)alkanamide (=S-(3-amino-1,2-dimethyl-3-oxopropyl) ethanethioate)'anti'-4h formed in the Michael addition, which was identified via the Karplus equation analysis, and confirmed by X-ray diffraction analysis. The current route is an efficient method to synthesize diverse substituted homotaurines, including 1-, 2-, and N-monosubstituted, as well as 1,2-, 1,N-, 2,N-, and N,N-disubstituted homotaurines (Table). Copyright
Bifunctional water activation for catalytic hydration of organonitriles
Daw, Prosenjit,Sinha, Arup,Rahaman, S. M. Wahidur,Dinda, Shrabani,Bera, Jitendra K.
experimental part, p. 3790 - 3797 (2012/06/18)
Treatment of [Rh(COD)(μ-Cl)]2 with excess tBuOK and subsequent addition of 2 equiv of PIN?HBr in THF afforded [Rh(COD)(κC2-PIN)Br] (1) (PIN = 1-isopropyl-3-(5,7-dimethyl-1, 8-naphthyrid-2-yl)imidazol-2-ylidene, COD = 1,5-cyclooctadiene). The X-ray structure of 1 confirms ligand coordination to "Rh(COD)Br" through the carbene carbon featuring an unbound naphthyridine. Compound 1 is shown to be an excellent catalyst for the hydration of a wide variety of organonitriles at ambient temperature, providing the corresponding organoamides. In general, smaller substrates gave higher yields compared with sterically bulky nitriles. A turnover frequency of 20 000 h-1 was achieved for the acrylonitrile. A similar Rh(I) catalyst without the naphthyridine appendage turned out to be inactive. DFT studies are undertaken to gain insight on the hydration mechanism. A 1:1 catalyst-water adduct was identified, which indicates that the naphthyridine group steers the catalytically relevant water molecule to the active metal site via double hydrogen-bonding interactions, providing significant entropic advantage to the hydration process. The calculated transition state (TS) reveals multicomponent cooperativity involving proton movement from the water to the naphthyridine nitrogen and a complementary interaction between the hydroxide and the nitrile carbon. Bifunctional water activation and cooperative proton migration are recognized as the key steps in the catalytic cycle.
I2-TEMPO as an efficient oxidizing agent for the one-pot conversion of alcohol to amide using FeCl3 as the catalyst
Das, Rima,Chakraborty, Debashis
experimental part, p. 48 - 53 (2012/08/28)
A high yield one-pot method for the synthesis of amides from alcohols is described. The aldehyde was generated in situ using iodine-TEMPO as oxidizing agent followed by intermediate oxime formation through reaction with NH 2OH?HCl and finally rearrangement of oxime catalyzed by FeCl3.
FeIII-catalyzed synthesis of primary amides from aldehydes
Gowda, Ravikumar R.,Chakraborty, Debashis
supporting information; experimental part, p. 2226 - 2229 (2011/06/17)
A direct synthetic route for the transformation of aldehydes into primary amides in the presence of catalytic amounts of FeCl3 in water is described. A direct synthetic route for the transformation of aldehydes into primary amides in the presence of catalytic amounts of FeCl3 in water is described. Copyright
Efficient nitrile hydration mediated by RuII catalysts in micellar media
Cavarzan, Alessandra,Scarso, Alessandro,Strukul, Giorgio
experimental part, p. 790 - 794 (2010/09/05)
Efficient nitrile hydration to the corresponding amide derivatives is observed in water using poorly soluble [RuCl2(η6- arene)(PR3)] catalysts 1 with the aid of surfactants to ensure substrate and catalyst solubilization, and enabling ligand effect study on catalytic activity. Amide yields of 40 to 95% can be observed with a variety of aromatic and aliphatic nitriles using the optimized catalyst system, [RuCl 2(p-cymene)(PPh2OEt)]/Triton X-114. Catalyst separation and recycling is possible.
Enzymatic nitrile hydrolysis catalyzed by nitrilase ZmNIT2 from maize. An unprecedented β-hydroxy functionality enhanced amide formation
Mukherjee, Chandrani,Zhu, Dunming,Biehl, Edward R.,Parmar, Rajiv R.,Hua, Ling
, p. 6150 - 6154 (2007/10/03)
To explore the synthetic potential of nitrilase ZmNIT2 from maize, the substrate specificity of this nitrilase was studied with a diverse collection of nitriles. The nitrilase ZmNIT2 showed high activity for all the tested nitriles except benzonitrile, producing both acids and amides. For the hydrolysis of aliphatic, aromatic nitriles, phenylacetonitrile derivatives and dinitriles, carboxylic acids were the major products. Unexpectedly, amides were found to be the major products in nitrilase ZmNIT2-catalyzed hydrolysis of β-hydroxy nitriles. The hydrogen bonding between the hydroxyl group and nitrogen in the enzyme-substrate complex intermediates that disfavors the loss of ammonia and formation of acyl-enzyme intermediate, which was further hydrolyzed to acid, was proposed to be responsible for the unprecedented β-hydroxy functionality assisted high yield of amide formation.
Niobium pentachloride promoted conversion of carboxylic acids to carboxamides: Synthesis of the 4-aryl-1,2,3,4-tetrahydroisoquinoline alkaloid structures
Nery, Marcelo S.,Ribeiro, Renata P.,Lopes, Claudio C.,Lopes, Rosangela S. C.
, p. 272 - 276 (2007/10/03)
A practical method for the conversion of carboxylic acids to the corresponding carboxamides mediated by niobium pentachloride under mild conditions is described. The synthesis of the 4-aryl-1,2,3,4-tetrahydroisoquinoline alkaloid structures was accomplished via benzylic lithiation of N-methyl-3,4-dimethoxy-2-(4′-methoxybenzyl)benzamide.
Synthesis and Reactions of Iodo Lactams
Knapp, Spencer,Levorse, Anthony T.
, p. 4006 - 4014 (2007/10/02)
The synthesis of a series of iodo lactams has been achieved by a new cyclization method that depends on generating N,O-bis(trimethylsilyl)imidate derivatives as intermediates.Treatment of an unsaturated amide with trimethylsilyl triflate in pentane and then iodine in tetrahydrofuran gives the iodo lactam.Some reactions of this new difunctional group with bases, nucleophiles, and Michael acceptors leading to functionalized or elaborated lactams are presented.In general, iodo lactams undergo direct SN2 reactions with reactive (but weakly basic) nucleophiles like azide and triphenylphosphine and elimination or decomposition in the presence of bases or basic nucleophiles.Sodium hydride may be used to generate an N-acylaziridine intermediate, which can be opened with azide to deliver an azido lactam with overall retention of stereochemistry.Silver-assisted solvolysis of iodo lactams gives the hydroxy lactams with retention of configuration, probably also because of participation by the lactam nitrogen.The sodium salt of 5-(iodomethyl)-2-pyrrolidinone (3), generated at -20 deg C, undergoes an annulation reaction with unsaturated esters (but not sulfones), leading to pyrrolizidine derivatives.
