- Trans-3-Hydroxy-4-morpholinopiperidine - The pH-triggered conformational switch with a double flip
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Derivatives of trans-3-hydroxy-4-aminopiperidine are suggested as potential pH-sensitive conformational switches able to perform two consecutive flips (or flip-flop) when basicity/acidity of solution changes. Such a double switch of conformation was detected by 1H NMR for a model compound - trans-3-hydroxy-4-morpholinopiperidine. A combination of hydrogen bonding and electrostatic/dipole-dipole interactions was suggested for rationalization. Computational studies provided additional insight into the complex intra- and intermolecular forces that determine the relative stabilities of conformers. In similar structures an incorporated trans-3-hydroxy-4-aminopiperidine moiety can serve as a conformational pH-trigger when equipped with substituents designed to perform certain geometry-dependent functions, for example, as cation chelators or as lipid tails.
- Samoshin, Andrey V.,Joo, Hyun,Korneichuk, Andrei Ya,Veselov, Ivan S.,Grishina, Galina V.,Samoshin, Vyacheslav V.
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- Fliposomes: New amphiphiles based on trans-3,4-bis(acyloxy)-piperidine able to perform a pH-triggered conformational flip and cause an instant cargo release from liposomes
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Amphiphilic trans-3,4-bis(acyloxy)-1-benzylpiperidines able to perform a pH-triggered conformational flip (flipids) have been suggested as components of a new type of pH-sensitive liposomes (fliposomes). According to 1H NMR, their acid-induced conformational flip occurs in methanol-d4 when the apparent pD decreases from 6 to 3. The protonation-generated intramolecular hydrogen bond and electrostatic interactions make the conformer with axial acyloxy-groups predominant, which drastically increases the separation of hydrocarbon chains. The power of this trigger was estimated as ≥10 kJ/mol. This flip perturbs the liposome membrane causing rapid release of the liposome cargo specifically in response to lowered pH. The pH-sensitive fliposomes containing one of these flipids, POPC and PEG-ceramide, and loaded with ANTS/DPX performed a content release within a few seconds at pH 5 demonstrating a potential of the piperidine derivatives as pH-switches for the design of liposomes for drug/gene delivery.
- Samoshin, Andrey V.,Veselov, Ivan S.,Chertkov, Vyacheslav A.,Yaroslavov, Alexander A.,Grishina, Galina V.,Samoshina, Nataliya M.,Samoshin, Vyacheslav V.
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The 3,3-bis(trimethylsilyl)propene reacts with iminium ions (generated in situ from primary amines) by an aminomethylation-desilylation process and a subsequent cyclization, leading to N-alkyl-1,2,3,6-tetrahydropyridines as principal products. Tetrahydro-1,3-oxazines with a bis(trimethylsilyl)methyl group may also be observed. When primary amines with a tertiary group are used, the reaction leads only to ω-aminovinylsilanes, the steric hindrance inhibiting the progression of the reaction.
- Princet, Bruno,Anselme, Gilles,Pornet, Jacques
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- Trans-3,4-diacetoxypiperidine as a model for novel pH-triggered conformational switches
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An acid-induced conformational flip of trans-3,4-diacetoxy-1- benzylpiperidine has been determined by 1H NMR. It occurs while the apparent pH (pD) of the d4-methanol solution decreases from 6 to 3. Due to an intramolecular hydrogen bond, the conformer with axial position of both acetoxy groups becomes strongly predominant. The separation of the acetoxy groups increases drastically. Thus, in similar structures an incorporated trans-3,4-disubstituted piperidine moiety can serve as a conformational pH-trigger when equipped with substituents designed to perform certain geometry-dependent functions, for example, as cation chelators or as lipid tails. The power of this trigger was estimated as ～10 kJ/mol.
- Samoshin, Andrey V.,Veselov, Ivan S.,Huynh, Leyna,Shestakova, Alla K.,Chertkov, Vyacheslav A.,Grishina, Galina V.,Samoshin, Vyacheslav V.
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- PRMT5 INHIBITORS
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The present invention provides a compound selected from: compounds A, B, C, D and the pharmaceutically acceptable salts, esters, and prodrugs thereof, which are PRMT5 inhibitors. Also provided are methods of making compounds disclosed herein, pharmaceutic
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- PRMT5 INHIBITORS
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The present invention provides a compound of Formula (I) and the pharmaceutically acceptable salts, esters, and prodrugs thereof, which are PRMT5 inhibitors. Also provided are methods of making compounds of Formula I, pharmaceutical compositions comprising compounds of Formula I, and methods of using these compounds to treat cancer, sickle cell, and hereditary persistence of foetal hemoglobin (HPFH) mutations.
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- ENANTIOMERIC COMPOUNDS
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The present invention relates to enantiomeric compounds, their use in stereospecific reactions and to a method of preparing enantiomeric compounds.
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- Normal Alpha Olefin Synthesis Using Dehydroformylation or Dehydroxymethylation
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The present invention discloses processes for producing normal alpha olefins, such as 1-hexene, 1-octene, 1-decene, and 1-dodecene in a multistep synthesis scheme from another normal alpha olefin. Also disclosed are reactions for converting aldehydes, primary alcohols, and terminal vicinal diols into normal alpha olefins.
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Paragraph 0127; 0128; 0129
(2019/09/06)
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- Oxidative Dehydroxymethylation of Alcohols to Produce Olefins
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Catalyst compositions for the conversion of aldehyde compounds and primary alcohol compounds to olefins are disclosed herein. Reactions include oxidative dehydroxymethylation processes and oxidative dehydroformylation methods, which are beneficially conducted in the presence of a sacrificial acceptor of H2 gas, such as N,N-dimethylacrylamide.
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Paragraph 0057; 0058
(2019/09/06)
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- N-benzyl-tetrahydropyridine compound and preparation method thereof
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The invention provides an N-benzyl-tetrahydropyridine compound and a preparation method thereof, and the preparation method comprises the following steps: S1, adding benzyl bromide into a pyridine compound to carry out nucleophilic substitution reaction t
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- A comparison between KbH4 and NaBH4 in their reduction of pyridinium salts
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This paper compares potassium borohydride and sodium borohydride in the reduction of pyridinium salts to tetrahydropyridines. The results indicate that potassium borohydride is more suitable for this reaction with low costs, mild reaction conditions and i
- Quan, Hao,Zhu, Bin,Li, Xiaolin,Zhan, Li,Luo, Yu
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p. 1244 - 1250
(2019/12/23)
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- Tandem Catalysis: Transforming Alcohols to Alkenes by Oxidative Dehydroxymethylation
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We report a Rh-catalyst for accessing olefins from primary alcohols by a C-C bond cleavage that results in dehomologation. This functional group interconversion proceeds by an oxidation-dehydroformylation enabled by N,N-dimethylacrylamide as a sacrificial acceptor of hydrogen gas. Alcohols with diverse functionality and structure undergo oxidative dehydroxymethylation to access the corresponding olefins. Our catalyst protocol enables a two-step semisynthesis of (+)-yohimbenone and dehomologation of feedstock olefins.
- Wu, Xuesong,Cruz, Faben A.,Lu, Alexander,Dong, Vy M.
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supporting information
p. 10126 - 10130
(2018/08/23)
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- Method for preparing N-substituted-1,2,3,6-tetrahydropyridine
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The invention discloses a method for preparing N-substituted-1,2,3,6-tetrahydropyridine and belongs to the technical field of organic chemistry. N-substituted-4-piperidinol as a raw material reacts with triphenylphosphine and azodicarbonic acid diester, alcoholic hydroxyl groups are converted into alkenyl groups, and N-substituted-1,2,3,6-tetrahydropyridine is prepared. The method has the advantages that the raw materials are easily available, the operation is simple and convenient, the product purity is high, demands of the conventional method for high-temperature condition and highly toxic chemicals are avoided, and the method has potential route advantage.
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Paragraph 0015; 0016; 0017; 0018; 0022
(2018/05/16)
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- Total synthesis of (±)-20: S -hydroxy-1,2-dehydro-pseudoaspidospermidine via a C-H activation/transannular cyclization strategy
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A total synthesis to the pseudoaspidospermidine family via a C-H activation/transannular cyclization strategy has been accomplished. The applicability of this approach is showcased in the concise synthesis (ten steps) of (±)-20S-hydroxy-1,2-dehydro-pseudoaspidospermidine (4) starting from literature known compound 11. Via a joint synthetic sequence we were also able to address the related iboga alkaloid (±)-isovelbanamine (7) in nine steps. Key features of this synthesis are a transannular cyclization to generate the pseudoaspidospermidine skeleton (C-H activation) and a Witkop photocyclization reaction providing a 9-membered lactam. It is also worth mentioning that the joint synthetic sequence can be carried out on a multigram scale.
- Leitner, Christian,Gaich, Tanja
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supporting information
p. 7451 - 7453
(2017/07/12)
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- Asymmetric Syntheses of (-)-ADMJ and (+)-ADANJ: 2-Deoxy-2-amino Analogues of (-)-1-Deoxymannojirimycin and (+)-1-Deoxyallonojirimycin
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The asymmetric syntheses of (-)-ADMJ and (+)-ADANJ, the 2-deoxy-2-amino analogues of (-)-1-deoxymannojirimycin and (+)-1-deoxyallonojirimycin, are described herein. Methodology for the ring-closing iodoamination of bishomoallylic amines followed by in situ ring-expansion (via intramolecular ring-opening of the corresponding aziridinium intermediates with a tethered carbamate moiety) to give oxazolidin-2-ones was initially optimized on a model system. Subsequent application of this methodology to two enantiopure bishomoallylic amines (which were produced via aminohydroxylation of an α,β-unsaturated ester, partial reduction, and reaction of the corresponding aldehyde with vinylmagnesium bromide) also proceeded with concomitant N-debenzylation to afford the corresponding diastereoisomerically pure (>99:1 dr) oxazolidin-2-ones. Subsequent deprotection of these enantiopure templates gave (-)-ADMJ and (+)-ADANJ as single diastereoisomers in 16% and 24% overall yield, respectively.
- Davies, Stephen G.,Figuccia, Aude L. A.,Fletcher Paul, Ai M.,Roberts,Thomson, James E.
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p. 6481 - 6495
(2016/08/16)
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- Rh-catalyzed C-C bond cleavage by transfer hydroformylation
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The dehydroformylation of aldehydes to generate olefins occurs during the biosynthesis of various sterols, including cholesterol in humans. Here, we implement a synthetic version that features the transfer of a formyl group and hydride from an aldehyde substrate to a strained olefin acceptor. A Rhodium(Xantphos)(benzoate) catalyst activates aldehyde carbon-hydrogen (C-H) bonds with high chemoselectivity to trigger carbon-carbon (C-C) bond cleavage and generate olefins at low loadings (0.3 to 2 mole percent) and temperatures (22° to 80°C). This mild protocol can be applied to various natural products and was used to achieve a three-step synthesis of (+)-yohimbenone. A study of the mechanism reveals that the benzoate counterion acts as a proton shuttle to enable transfer hydroformylation.
- Murphy, Stephen K.,Park, Jung-Woo,Cruz, Faben A.,Dong, Vy M.
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- Reactions of Tertiary Allylic Amines and Dichlorocarbenes
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In this article, a study on reactions of tertiary allylic amines and dichlorocarbenes had been described. Tertiary allylic amines could result from an interesting de-N-allylation/formylation reaction under the treatment of dichlorocarbenes. Notably, amines containing steric substituents or electron-deficient aromatic substituents on the nitrogen will go through cyclopropanations of the carbon-carbon double bond.
- Wang, Meili,Xiao, Fenfen,Bai, Yinjuan,Hu, Xiangdong
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supporting information
p. 2259 - 2265
(2015/09/22)
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- COMPOSITIONS COMPRISING THIENOPYRIMIDINE AND THIENOPYRIDINE COMPOUNDS AND METHODS OF USE THEREOF
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The present invention relates generally to thienopyrimidine and thienopyridine class compounds and methods of use thereof. In particular embodiments, the present invention provides compositions comprising thienopyrimidine class compounds and methods of us
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Paragraph 0182; 0188; 0189
(2014/09/29)
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- INHIBITORS OF BRUTON'S TYROSINE KINASE
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The present invention provides a compound, solid forms, and compositions thereof, which are useful as inhibitors of Bruton's tyrosine kinase and which exhibit desirable characteristics for the same. The present invention also provides methods of making provided compound and solid forms.
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- Selection and scale-Up evaluation of an alternative route to (-)-(3R,4R)-1-Benzyl-4-(benzylamino)piperidin-3-ol
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An efficient, scalable synthesis of (-)-(3R,4R)-1-benzyl-4-(benzylamino) piperidin-3-ol (4) is described. Reduction of the pyridinium salt prepared from pyridine and benzyl chloride generated the corresponding tetrahydropyridine derivative. A two-stage epoxidation, followed by ring-opening of the epoxide with BnNH2, established the regiochemistry of the amino alcohol and served to set the trans-relationship between the amine and the hydroxyl group. The resulting racemic intermediate was then resolved by salt formation with (R)-O-acetyl mandelic acid. The process produced the O-acetyl mandelic acid salt of (-)-4 in 27% overall yield from benzyl chloride.
- Young, Ian S.,Ortiz, Adrian,Sawyer, James R.,Conlon, David A.,Buono, Frederic G.,Leung, Simon W.,Burt, Justin L.,Sortore, Eric W.
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p. 1558 - 1565
(2013/02/25)
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- Diastereodivergent hydroxyfluorination of cyclic and acyclic allylic amines: Synthesis of 4-deoxy-4-fluorophytosphingosines
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A diastereodivergent hydroxyfluorination protocol enabling the direct conversion of some conformationally biased allylic amines to the corresponding diastereoisomeric amino fluorohydrins has been developed. Sequential treatment of a conformationally biased allylic amine with 2 equiv of HBF 4·OEt2 followed by m-CPBA promotes epoxidation of the olefin on the face proximal to the amino group under hydrogen-bonded direction from the in situ formed ammonium ion. Regioselective and stereospecific epoxide ring-opening by transfer of fluoride from a BF 4- ion (an SN2-type process at the carbon atom distal to the ammonium moiety) then occurs in situ to give the corresponding amino fluorohydrin. Alternatively, an analogous reaction using 20 equiv of HBF4·OEt2 results in preferential epoxidation of the opposite face of the olefin, which is followed by regioselective and stereospecific epoxide ring-opening by transfer of fluoride from a BF 4- ion (an SN2-type process at the carbon atom distal to the ammonium moiety). The synthetic utility of this methodology is demonstrated via its application to a synthesis of 4-deoxy-4-fluoro-l-xylo- phytosphingosine and 4-deoxy-4-fluoro-l-lyxo-phytosphingosine, each in five steps from Garner's aldehyde.
- Cresswell, Alexander J.,Davies, Stephen G.,Lee, James A.,Morris, Melloney J.,Roberts, Paul M.,Thomson, James E.
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p. 7262 - 7281
(2012/10/30)
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- METHOD FOR PRODUCING N-SUBSTITUTED-TRANS-4-AZIDOPIPERIDINE-3-OL
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An N-substituted-trans-4-azidopiperidin-3-ol represented by formula (II-1) R1 is as defined below, which is useful as a pharmaceutical intermediate and so on, is produced by reacting an N-substituted-3,4-epoxypiperidine represented by formula (
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Page/Page column 7
(2011/07/29)
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- PROCESS FOR PRODUCING 1-SUBSTITUTED TRANS-4-(SUBSTITUTED AMINO) PIPERIDIN-3-OL
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A process is provided for producing a 1-substituted trans-4-(substituted amino)piperidin-3-ol represented by formula (III-1): The process includes a step of reacting a 1-substituted-3,4-epoxypiperidine represented by formula (I): with an amine compound re
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Page/Page column 11
(2011/08/03)
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- Time-dependent slowly-reversible inhibition of monoamine oxidase A by N-substituted 1,2,3,6-tetrahydropyridines
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A novel class of N-substituted tetrahydropyridine derivatives was found to have multiple kinetic mechanisms of monoamine oxidase A inhibition. Eleven structurally similar tetrahydropyridine derivatives were synthesized and evaluated as inhibitors of MAO-A and MAO-B. The most potent MAO-A inhibitor in the series, 2,4-dichlorophenoxypropyl analog 12, displayed time-dependent mixed noncompetitive inhibition. The inhibition was reversed by dialysis, indicating reversible enzyme inhibition. Evidence that the slow-binding inhibition of MAO-A with 12 involves a covalent bond was gained from stabilizing a covalent reversible intermediate product by reduction with sodium borohydride. The reduced enzyme complex was not reversible by dialysis. The results are consistent with slowly reversible, mechanism-based inhibition. Two tetrahydropyridine analogs that selectively inhibited MAO-A were characterized by kinetic mechanisms differing from the kinetic mechanism of 12. As reversible inhibitors of MAO-A, tetrahydropyridine analogs are at low risk of having an adverse effect of tyramine-induced hypertension.
- Wichitnithad, Wisut,O'Callaghan, James P.,Miller, Diane B.,Train, Brian C.,Callery, Patrick S.
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p. 7482 - 7492
(2012/02/02)
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- High regiocontrol in the nucleophilic ring opening of 1-aralkyl-3,4- epoxypiperidines with amines - A short-step synthesis of 4- fluorobenzyltrozamicol and novel anilidopiperidines
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Nucleophilic ring-opening reactions of three 1-aralkyl-3,4-epoxypiperidines with a series of aliphatic and aromatic amines have been investigated. Reactions in protic solvents, preferably 2-propanol, gave rise to 3-amino-piperidin-4-ols in ratios up to 20:1. Accordingly, 4- fluorobenzyltrozamicol, a highly potent ligand for the vesicular acetylcholine transporter was obtained directly from an epoxide ring opening in one step, without the need of chromatographic separation. Reactions in acetonitrile assisted by Li-salts, most suitable with LiBr, led regioselectively to trans-4-amino-piperidin-3-ols in high yields. N-Phenethyl substituted anilino-piperidinols as easily obtained by this method were converted into a series of new β-hydroxy substituted anilidopiperidines.
- Scheunemann, Matthias,Hennig, Lothar,Funke, Uta,Steinbach, J?rg
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p. 3448 - 3456
(2011/06/20)
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- Fatty acid amide hydrolase inhibitors. 2. Novel synthesis of sterically hindered azabenzhydryl ethers and an improved synthesis of VER-156084
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We report an improved synthesis of the fatty acid amide hydrolase (FAAH) inhibitor VER-156084. The key step is a novel, environmentally benign etherification to form an unusual, highly hindered azabenzhydryl ether. The method is applied to a variety of pr
- Roughley, Stephen D.,Hart, Terance
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scheme or table
p. 5191 - 5194
(2010/11/16)
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- A convenient racemic synthesis of two isomeric tetrahydropyridyl alkaloids: Isoanatabine and anatabine
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(Chemical Equation Presented) Anatabine is a major alkaloid in Nicotiana tabacum and its isomer, isoanatabine, was recently found in a marine worm. Reduction of 1-methylpyridinium iodide with sodium borohydride gave 1-methyl-3-piperideine, which was transformed with hydrogen peroxide into the N-oxide. Reaction of the N-oxide successively with trifluoroacetic anhydride and potassium cyanide gave 2-cyano-1-methyl-3-piperideine. Its reaction with 3-pyridylmagnesium chloride gave (±)-N-methyl-isoanatabine. This was transformed with m-chloroperbenzoic acid into the N-oxide which was N-demethylated with iron(II) sulfate, giving (±)-isoanatabine. The successive applications of literature procedures for the N-demethylation by decomposition of N-oxide contributed to the knowledge of the mechanism of this oxidative rearrangement. On the other hand, the reduction of 1-methylpyridinium iodide with sodium borohydride and with potassium cyanide present since the start of the reaction in a two layer ether-water system, gave 2-cyano-1-methyl-4-piperideine. This was transformed into (±)-anatabine by the same sequence of reactions used for the synthesis of (±)- isoanatabine.
- Rouchaud, Anne,Kem, William R.
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body text
p. 569 - 581
(2010/09/05)
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- Straightforward and scalable synthesis of orthogonally protected 3,7-diazabicyclo[4.1.0]heptane
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Orthogonally N-protected (Boc and Cbz) 3,4-aziridinopiperidine is a versatile building block for the synthesis of 4-substituted 3-aminopiperidines, which are compounds with a high potential for biological activity. A multigram synthesis over five steps, starting with extraordinarily simple materials (pyridine and benzyl chloride), was developed. Georg Thieme Verlag Stuttgart.
- Schramm, Heiko,Pavlova, Maria,Hoenke, Christoph,Christoffers, Jens
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experimental part
p. 1659 - 1662
(2010/01/19)
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- SYNTHESIS OF UNSATURATED PIPERIDINES FROM PIPERIDONES WITH A SILYL REAGENT
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Syntheses of unsaturated piperidines from piperidones through a silyl pipehdine reagent via the Shapiro reaction and palladium-catalyzed cross- coupling reactions with organo halides.
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Page/Page column 15-16
(2008/12/07)
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- Development of two diastereoselective routes towards trans-4-aminomethyl-piperidin-3-ol building blocks
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Two diastereoselective, scaleable routes towards trans-3,4-disubstituted piperidines with a 4-hydroxymethyl-3-hydroxy or 4-aminomethyl-3-hydroxy substitution pattern are being described. In the first route, the 3,4-trans configuration was introduced regio- and diastereoselectively via a hydroboration/oxidation sequence starting from 4-hydroxymethylpyridine. In the second route, regioselective epoxide ring opening of N-benzyl-3,4-epoxy-piperidine was achieved with LiCN, in situ generated from acetocyanohydrin and LiNH2. The regioselectivity of both the hydroboration and the epoxide ring opening was positively influenced by the presence of the basic piperidine nitrogen. Both routes have been optimized to be performed at large scale.
- Gijsen, Harrie J.M.,De Cleyn, Michel J.A.,Love, Christopher J.,Surkyn, Michel,Van Brandt, Sven F.A.,Verdonck, Marc G.C.,Moens, Luc,Cuypers, Jef,Bosmans, Jean-Paul R.M.A.
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p. 2456 - 2464
(2008/09/18)
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- Synthesis of 4-arylpiperidines from 1-benzyl-4-piperidone: Application of the shapiro reaction and alkenylsilane cross-coupling
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Equation Presented 1-Benzyl-3,4-unsaturated-4-piperidinyl benzyldimethylsilane has been prepared and observed to readily undergo palladium-catalyzed cross-coupling reactions with a variety of aryl iodides and aryl bromides to generate 3,4-unsaturated 4-arylpiperidines, often at ambient temperature.
- Morrill, Christie,Mani, Neelakandha S.
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p. 1505 - 1508
(2008/02/02)
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- Synthesis and antibacterial activity of novel fluoroquinolones containing substituted piperidines
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The design and synthesis of new fluoroquinolone antibacterial agents having substituted piperidine rings at the C-7 position are described. Most of the new compounds demonstrated high in vitro antibacterial activity. Several of them exhibited significant activities against Gram-positive organisms, which were more potent than those of gemifloxacin, Linezolid, and vancomycin.
- Dang, Zhao,Yang, Yushe,Ji, Ruyun,Zhang, Shuhua
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p. 4523 - 4526
(2008/02/12)
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- Transformation of 1,2,5,6-tetrahydropyridines with mycellar fungi
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It has been shown that on biotransformation of a series of 1,2,5,6-tetrahydropyridines with strains of the mycellar fungi Cunninghamella verticillata VKPM F-430, Beauveria bassiana ATCC 7159, and Penicillium simplicissimum KM-16, the culture of Cunninghamella verticillata possesses the greatest transforming activity and selectivity. With the aid of the latter practically quantitative oxidation of 1,2,5,6-tetrahydropyridines occurs into the corresponding trans-diol. The structure and spatial disposition of trans-1-benzyl-3,4-dihydroxypiperidine was demonstrated by data of chromato-mass spectrometric analysis and high resolution NMR spectra and was confirmed by comparison with an authentic sample obtained by an alternate synthesis using the oxidation of 1-benzyl-1,2,5,6-tetrahydropyridine with trifluoroperacetic acid.
- Terentiev,Zilberstein,Borisenko,Shmorgunov,Piskunkova,Grishina
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p. 885 - 890
(2007/10/03)
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- Selective cleavage of N-benzyl-protected secondary amines by triphosgene
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A series of competition experiments has revealed that selective cleavage of N-benzyl-protected secondary amines can be achieved with triphosgene, thereby providing a useful range of carbamoyl chlorides.
- Banwell, Martin G.,Coster, Mark J.,Harvey, Michael J.,Moraes, John
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p. 613 - 616
(2007/10/03)
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- Preparation of cyclic amines by the titanocene(II)-promoted cyclization of thioacetals having a carbon-carbon double bond
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Nitrogen-containing unsaturated heterocycles were obtained in good yields by the titanocene(II)-promoted ring-closing metathesis of the amines possessing an olefin and a diphenyl thioacetal moieties.
- Fujiwara, Tooru,Kato, Yoshiko,Takeda, Takeshi
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p. 147 - 150
(2007/10/03)
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- Reductive amination of piperidines with aldehydes using borane-pyridine
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Borane-pyridine complex (BAP) was found to be an excellent replacement for NaCNBH3 in the Borch reduction. Assorted aromatic, heterocyclic and aliphatic aldehydes were reacted with various substituted piperidines using standardized conditions.
- Moormann
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p. 789 - 795
(2007/10/02)
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- Preparation of enantioenriched tetrahydropyridines by iminium ion-vinylsilane cyclizations
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Tetrahydropyridines can be prepared from (S)-amino acids in high enantiomeric purity as outlined in equation 1.
- Castro,Overman,Zhang,Mariano
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p. 5243 - 5246
(2007/10/02)
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- Hydroboration. 86. Convenient Conversion of Aldehydes and Ketones into the Corresponding Alkenes via Hydroboration of their Enamines. A Remarkably Simple Synthesis of Either (Z)- or (E)-Alkenes
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Aldehydes and ketones are converted into the corresponding alkenes via hydroboration of their enamines.Hydroboration of aldehyde enamines by 9-borabicyclononane (9-BBN), followed by methanolysis, affords the corresponding terminal alkenes in 75-90percent yields.Unsaturated aldehyde enamines produce the corresponding dienes under these conditions.Enamines derived from substituted cyclic ketones and heterocyclic ketones are readily accommodated in this reaction to afford the corresponding alkenes in very good yields.The synthesis of pure (Z)- or (E)-alkenes is readily achieved from the same acyclic ketone enamine by modification of the hydroboration-elimination procedure: (A) hydroboration by 9-BBN followed by methanolysis or (B) hydroboration by borane methyl sulfide (BMS) followed by methanolysis and hydrogen peroxide oxidation.Mechanistic rationale is provided.
- Singaram, Bakthan,Rangaishenvi, Milind V.,Brown, Herbert C.,Goralski, Christian G.,Hasha, Dennis L.
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p. 1543 - 1549
(2007/10/02)
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- Synthesis of alkenes from enamines via hydroboration
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Alkenes are prepared by the hydroboration of enamines followed by an elimination reaction to form the alkene. This process has wide applicability and is useful for the stereospecific synthesis of [Z] isomers. It is preferred to use 9-borabicyclo[3.3.1 nonane as the hydroborating agent and to use methanol to catalyze the elimination reaction.
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- 2-Cyano-Δ3-piperideines. 12. Stereochemistry of Formation of N-Benzyl-2-cyano-Δ3-piperideines and Facile Isomerization on Alumina to 2-Cyano-Δ4-piperideines. A Potentially General Route to the Synthesis of 2,6-Disubstitute
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The reaction of the piperideine N-oxides 1a-f with trifluoroacetic anhydride in CH2Cl2 at 0 deg C (Polonovski-Potier reaction) led to the formation of the N-benzyl-2-cyano-Δ3-piperideines 3a-f.Epimeric mixtures were obtained for the amino nitri
- Bonin, Martine,Romero, Jose Ricardo,Grierson, David S.,Husson, Henri-Philippe
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p. 2392 - 2400
(2007/10/02)
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- Synthesis and Dynamic NMR Studies of the 3,7-Diazabicycloheptane System
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A new bicyclic system, 3,7-diazabicycloheptane, has been prepared from 3-(ethoxycarbonyl)-7,3-oxazabicycloheptane by reaction with sodium azide and reduction of the resulting tosyloxy azide with lithium aluminum hydride.The molecule can exis
- Majchrzak, Michal,Kotelko, Antoni,Lambert, Joseph B.
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p. 539 - 543
(2007/10/02)
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