- A facile synthesis of cyclic enecarbamates using Dess-Martin periodinane
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A simple and efficient synthesis of cyclic enecarbamates from ω-hydroxycarbamates via tandem oxidative cyclization-dehydration was achieved in 84% to quantitative yield using Dess-Martin periodinane in methylene chloride.
- Yu, Chengzhi,Hu, Longqin
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- Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route towardcontra-Thermodynamic Olefins
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We report here a mechanistically distinct tactic to carry E2-type eliminations on alkyl halides. This strategy exploits the interplay of α-aminoalkyl radical-mediated halogen-atom transfer (XAT) with desaturative cobalt catalysis. The methodology is high-yielding, tolerates many functionalities, and was used to access industrially relevant materials. In contrast to thermal E2 eliminations where unsymmetrical substrates give regioisomeric mixtures, this approach enables, by fine-tuning of the electronic and steric properties of the cobalt catalyst, to obtain high olefin positional selectivity. This unprecedented mechanistic feature has allowed access tocontra-thermodynamic olefins, elusive by E2 eliminations.
- Zhao, Huaibo,McMillan, Alastair J.,Constantin, Timothée,Mykura, Rory C.,Juliá, Fabio,Leonori, Daniele
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supporting information
p. 14806 - 14813
(2021/09/18)
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- Backbone-Modified C2-Symmetrical Chiral Bisphosphine TMS-QuinoxP*: Asymmetric Borylation of Racemic Allyl Electrophiles
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A new C2-symmetrical P-chirogenic bisphosphine ligand with silyl substituents on the ligand backbone, (R,R)-5,8-TMS-QuinoxP*, has been developed. This ligand showed higher reactivity and enantioselectivity for the direct enantioconvergent borylation of cy
- Imamoto, Tsuneo,Ito, Hajime,Iwamoto, Hiroaki,Ozawa, Yu,Takenouchi, Yuta
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supporting information
p. 6413 - 6422
(2021/05/31)
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- β-Functionalization of Saturated Aza-Heterocycles Enabled by Organic Photoredox Catalysis
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The direct β-functionalization of saturated aza-heterocycles has remained a synthetic challenge because of the remote and unactivated nature of β-C-H bonds in these motifs. Herein, we demonstrate the β-functionalization of saturated aza-heterocycles enabl
- Holmberg-Douglas, Natalie,Choi, Younggi,Aquila, Brian,Huynh, Hoan,Nicewicz, David A.
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p. 3153 - 3158
(2021/04/06)
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- Iron-Catalyzed Tunable and Site-Selective Olefin Transposition
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The catalytic isomerization of C-C double bonds is an indispensable chemical transformation used to deliver higher-value analogues and has important utility in the chemical industry. Notwithstanding the advances reported in this field, there is compelling demand for a general catalytic solution that enables precise control of the C═C bond migration position, in both cyclic and acyclic systems, to furnish disubstituted and trisubstituted alkenes. Here, we show that catalytic amounts of an appropriate earth-abundant iron-based complex, a base and a boryl compound, promote efficient and controllable alkene transposition. Mechanistic investigations reveal that these processes likely involve in situ formation of an iron-hydride species which promotes olefin isomerization through sequential olefin insertion/β-hydride elimination. Through this strategy, regiodivergent access to different products from one substrate can be facilitated, isomeric olefin mixtures commonly found in petroleum-derived feedstock can be transformed to a single alkene product, and unsaturated moieties embedded within linear and heterocyclic biologically active entities can be obtained.
- Yu, Xiaolong,Zhao, Haonan,Li, Ping,Koh, Ming Joo
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supporting information
p. 18223 - 18230
(2020/12/04)
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- Electrochemical Scaled-up Synthesis of Cyclic Enecarbamates as Starting Materials for Medicinal Chemistry Relevant Building Bocks
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The electrochemical Shono oxidation of Boc-protected cyclic amines was revised. The conditions for scalable electrochemical synthesis of cyclic enecarbamates were found. The developed protocol included recycling of the full range of used reagents, favoring to E-factor reduction according to Green Chemistry requirements. The method opened the way for the convenient preparation of previously uncommon materials, which could become useful synthetic intermediates. Their synthetic potential was evaluated in [2+1] and [2+2] cycloadditions as well as electrophilic functionalization. Moreover, functionalized enecarbamates with carbonyl groups in β-position were used as latent 1,3-bielectrophiles in classical heterocyclizations. In a case of the hydrazine, the corresponding unusually decorated pyrazoles were prepared. The proposed methodology is a straightforward tool for the design and synthesis of Medicinal Chemistry relevant building blocks. As examples, 5-fluoro pipecolic and 3-fluoro isonipecotic acids were synthesized starting from Boc-protected esters of the pipecolic and the isonipecotic acids respectively; the 5-step approach to pyrazole containing α-aminoacids with different linkers between the aminoacidic and pyrazole moieties was elaborated based on the cheapest commercially available racemic and chiral cyclic α-aminoacids; the convenient approach to the functionalized tetrahydropyrido[3,4-d]pyridazines was proposed starting from Boc-protected ester of the isonipecotic acids. (Figure presented.).
- Tereshchenko, Oleksandr D.,Perebiynis, Maryana Y.,Knysh, Irina V.,Vasylets, Olesia V.,Sorochenko, Anna A.,Slobodyanyuk, Eugeniy Y.,Rusanov, Eduard B.,Borysov, Oleksandr V.,Kolotilov, Sergey V.,Ryabukhin, Sergey V.,Volochnyuk, Dmitriy M.
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supporting information
p. 3229 - 3242
(2020/07/06)
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- Synthesis and Structural Elucidation of 1,2-Disubstituted 3-Fluoropiperidines
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The work described details the reaction between Selectfluor and a series of 1-carbonyloxy and 1-sulfonyl 2-piperidines in order to generate 3-fluoro-2-methoxypiperidines 3a–f. Their subsequent reaction with allyltrimethylsilane, in the presence of BF3 and TiCl4, is then reported. Studies involving a combination of single-crystal X-ray crystallography and NMR spectroscopy indicate that the allylation process is cis-selective for both carbamate and sulfonamide variants and that optimal levels of diastereoselectivity are obtained using the N-2-nitrobenzene sulfonyl (2-Ns) group. In this manner, the synthesis of a series of 2-allyl 3-fluoro-substituted piperidines (5a, c–f) was achieved. The conversion of both the cis and trans-N-tosyl adducts (5d) into 3-fluorinated analogues of the natural products pelletierine (10) and coniine (11) is subsequently detailed.
- Evans, Paul,Fischer, Pauline,Müller-Bunz, Helge,Morris, Morgan
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- ?-C(sp2)-H alkylation of enamides using xanthate chemistry
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Access to the ?-amino-?,?-unsaturated acyl scaffold was established by applying xanthate chemistry to enamides. This original ?-C(sp2)-H alkylation is regioselective and exhibits broad substrate scope and good functional group tolerance. The la
- Bertho, Sylvain,Dondasse, Isma?l,Retailleau, Pascal,Nicolas, Cyril,Gillaizeau, Isabelle
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supporting information
p. 7129 - 7141
(2020/05/16)
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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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- Photoinduced Kochi Decarboxylative Elimination for the Synthesis of Enamides and Enecarbamates from N-Acyl Amino Acids
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Decarboxylative elimination of easily accessible N-acyl amino acids to provide enamide and enecarbamate building blocks has been realized through the combination of an organophotoredox catalyst and copper acetate as the terminal oxidant. This operationally simple process utilizes inexpensive and readily available reagents without preactivation of the carboxylic acid. Enamides and enecarbamates are now accessible directly from N-acyl amino acids consequently improving upon the utility of Kochi's oxidative decarboxylation of carboxylic acids.
- Cartwright, Kaitie C.,Lang, Simon B.,Tunge, Jon A.
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p. 2933 - 2940
(2019/03/26)
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- Manganese-Catalyzed Desaturation of N-Acyl Amines and Ethers
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Enamines and enol ethers are versatile synthons for chemical synthesis. While several methods have been developed to access such molecules, prefunctionalized starting materials are usually required, and direct desaturation methods remain rare. Herein, we report direct desaturation reactions of N-protected cyclic amines and cyclic ethers using a mild I(III) oxidant, PhI(OAc)2, and an electron-deficient manganese pentafluorophenylporphyrin catalyst, Mn(TPFPP)Cl. This system displays high efficiency for α,β-desaturation of various cyclic amines and ethers. Mechanistic probes suggest that the desaturation reaction occurs via an initial α-C-H hydroxylation pathway, which serves to protect the product from overoxidation.
- Li, Gang,Kates, Patrick A.,Dilger, Andrew K.,Cheng, Peter T.,Ewing, William R.,Groves, John T.
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p. 9513 - 9517
(2019/10/14)
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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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- Saturated Heterocyclic Aminosulfonyl Fluorides: New Scaffolds for Protecting-Group-Free Synthesis of Sulfonamides
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Cyclic saturated aminosulfonyl fluorides were synthesized as their HCl salts. The compounds were found to be stable upon storage and could be used for the protecting-group-free synthesis of sulfonamides. In the presence of the ?SO2F group, the nitrogen atom could be modified by means of acylation, arylation, or reductive amination to give products that have high potential for the synthesis of bioactive compounds.
- Zhersh, Sergey A.,Blahun, Oleksandr P.,Sadkova, Iryna V.,Tolmachev, Andrey A.,Moroz, Yurii S.,Mykhailiuk, Pavel K.
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supporting information
p. 8343 - 8349
(2018/06/04)
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- Synthesis of functionalised azepanes and piperidines from bicyclic halogenated aminocyclopropane derivatives
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A series of 6,6-dihalo-2-azabicyclo[3.1.0]hexane and 7,7-dihalo-2-azabicyclo[4.1.0]heptane compounds were prepared by the reaction of dihalocarbene species with N-Boc-2,3-dihydro-1H-pyrroles or -1,2,3,4-tetrahydropyridines. Monochloro substrates were synthesised as well, using a chlorine-to-lithium exchange reaction. The behaviour of several aldehydes and ketones under reductive amination conditions with deprotected halogenated secondary cyclopropylamines was investigated, showing that this transformation typically triggers cyclopropane ring cleavage to give access to interesting nitrogen-containing ring-expanded products.
- Chen, Cheng,Kattanguru, Pullaiah,Tomashenko, Olesya A.,Karpowicz, Rafa?,Siemiaszko, Gabriela,Bhattacharya, Ahanjit,Calasans, Vinícius,Six, Yvan
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p. 5364 - 5372
(2017/07/10)
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- Cobalt-Catalyzed Cross-Coupling of 3- and 4-Iodopiperidines with Grignard Reagents
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A cobalt-catalyzed cross-coupling between 3- and 4-iodopiperidines and Grignard reagents is disclosed. The reaction is an efficient, cheap, chemoselective, and flexible way to functionalize piperidines. This coupling was used as the key step to realize a short synthesis of (±)-preclamol. Some mechanistic investigations were conducted that highlight the formation of radical intermediates. Scaffold synthesis: A cobalt-catalyzed cross-coupling between iodopiperidines and Grignard reagents is reported (see scheme; PG=protecting group). A large variety of 3- and 4-substituted piperidines were synthesized and the method was applied to a short synthesis of (±)-preclamol. This work constitutes one of the rare examples of cross-couplings involving 3-halogeno piperidines.
- Gonnard, Laurine,Gurinot, Amandine,Cossy, Janine
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p. 12797 - 12803
(2015/09/01)
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- Synthesis of trifluoromethyl-substituted 3-azabicyclo[n.1.0]alkanes: Advanced building blocks for drug discovery
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Five CF3-substituted 3-azabicyclo[n.1.0]alkanes were synthesized by CuCl-mediated trifluoromethylcyclopropanation reaction of the corresponding cyclic enamides with CF3CHN2. Copyright
- Artamonov, Olexiy S.,Slobodyanyuk, Evgeniy Y.,Volochnyuk, Dmitriy M.,Komarov, Igor V.,Tolmachev, Andrey A.,Mykhailiuk, Pavel K.
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p. 3592 - 3599
(2014/06/23)
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- Iron-catalyzed oxidative C(3)-H functionalization of amines
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Fe-catalyzed direct dehydrogenative C(3)-functionalization of tertiary arylamines was developed via activation of the sp3 C(3)-H bond. The reaction is applicable to both cyclic and acyclic amines. The key process is the catalytic desaturative enamine formation from tertiary amines and position-selective C-C bond formation (addition to nitro olefins) at the β-carbon. Products can be converted to versatile and unique nitrogen-containing molecules.
- Takasu, Noriaki,Oisaki, Kounosuke,Kanai, Motomu
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p. 1918 - 1921
(2013/06/04)
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- Catalytic selective oxyamidation of cyclic enamides using nitrenes
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Yes, nitrenes did "N,O"! Intermolecular addition of nitrene to enecarbamates and enesulfonamides gives oxyamidated products in excellent yields of up to 98% and with good levels of stereoselectivity. Complete regioselectivity is also observed, leading to
- Gigant, Nicolas,Dequirez, Geoffroy,Retailleau, Pascal,Gillaizeau, Isabelle,Dauban, Philippe
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supporting information; experimental part
p. 90 - 94
(2012/02/16)
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- Hydrozirconation of four-, five-, six- and seven-membered N-alkoxycarbonyl lactams to lactamols
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A general, practical, and efficient reduction of four-, five-, six- and, seven-membered N-alkoxycarbonyl lactams to the aldehyde oxidation state is reported. The reduction methodology involves the hydrozirconation reaction by Cp2Zr(H)Cl under m
- Piperno, Anna,Carnovale, Caterina,Giofr, Salvatore V.,Iannazzo, Daniela
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supporting information; experimental part
p. 6880 - 6882
(2012/02/05)
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- The synthesis of piperidine nucleoside analogs - A comparison of several methods to access the introduction of nucleobases
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This work deals with the synthesis of piperidine and hydroxypiperidine analogs of nucleosides. Starting from commercially available 3-hydroxypiperidine, proline or 4-hydroxyproline, a series of piperidine derivatives of both purine and pyrimidine nucleobases was prepared. Various methods of nucleobase attachment were evaluated. The prepared compounds were tested for cytostatic, antibacterial, and antiviral properties but no significant activity was found.
- Kova?ková, Soňa,Dra?ínsky, Martin,Rejman, Dominik
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scheme or table
p. 1485 - 1500
(2011/04/15)
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- Regioselective and stereoselective copper(I)-Promoted allylation and conjugate addition of N -Boc-2-lithiopyrrolidine and N -Boc-2-lithiopiperidine
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Copper salts have been screened for transmetalation and electrophilic quench of N-tert-butoxycarbonyl-2-lithiopyrrolidine (N-Boc-2-lithiopyrrolidine) and N-Boc-2-lithiopiperidine, formed by deprotonation of N-Boc-pyrrolidine and N-Boc-piperidine, respectively. Transmetalation with zinc chloride then (lithium chloride solubilized) copper cyanide followed by allylation typically gives mixtures of regioisomers (SN2 and SN2′ products), whereas transmetalation with copper iodideTMEDA then allylation occurs regioselectively (SN2 mechanism). Addition to an enone or α,β-unsaturated ester occurs by 1,4-addition. Asymmetric deprotonation of N-Boc-pyrrolidine or dynamic resolution in the presence of a chiral ligand of N-Boc-2-lithiopiperidine followed by the zinc/copper chemistry was successful and gave the allylated pyrrolidine and piperidine products with good enantioselectivity, although use of the copper iodide chemistry resulted in some loss of enantiopurity. The chemistry provides formal syntheses of (+)-allosedridine, (+)-lasubine II, and (+)-pseudohygroline and has been used for the synthesis of (+)-coniine, (-)-pelletierine, (+)-coniceine, (-)-norhygrine, and the ant extract alkaloids cis- and trans-2-butyl-5- propylpyrrolidine.
- Coldham, Iain,Leonori, Daniele
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supporting information; experimental part
p. 4069 - 4077
(2010/08/20)
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- Concise asymmetric synthesis of (+)-febrifugine utilizing trans-selective intramolecular conjugate addition
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Intramolecular conjugate addition of γ-substituted (E)- α,β-unsaturated ketones with a Lewis acid (BF3· OEt2) selectively afforded trans-2,3-disubstituted piperidine derivatives. Chiral substrates were synthesized by Sharpless asymmetric dihydroxylation of the enamine; the antimalarial compound febrifugine was synthesized from the major product of the conjugate addition reaction. Georg Thieme Verlag Stuttgart.
- Sukemoto, Satoshi,Oshige, Miyo,Sato, Masahiro,Mimura, Ken-Ichiro,Nishioka, Hiromi,Abe, Hitoshi,Harayama, Takashi,Takeuchi, Yasuo
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experimental part
p. 3081 - 3087
(2009/04/07)
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- METHOD OF PRODUCING AMINOPHENOL COMPOUNDS
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The present invention provides an industrially advantageous method of producing aminophenol compounds represented by the formula (1) by a simple and easy procedure at a high yield and a high purity. The present invention provides a method of producing an aminophenol compound represented by the formula (1): (wherein each of R1 and R2, which may be the same or different, is a hydrogen atom, a substituted or unsubstituted lower alkyl group or the like; R1 and R2, taken together with the adjacent nitrogen atom, may form a 5- or 6-membered heterocycle with or without other intervening heteroatoms; the heterocycle may be substituted by 1 to 3 substituents selected from the group consisting of a hydroxyl group, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group and the like; and the hydroxyl group in the formula (1) is substituted on the 2- or 4-position to the amino group on the phenyl ring), which comprises allowing a cyclohexanedione compound represented by the formula (2) to react with an amine compound represented by the formula (3) (wherein R1 and R2 are as defined above), under a neutral or basic condition.
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Page/Page column 44-46
(2010/02/14)
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- Preparation and Suzuki-Miyaura coupling reactions of tetrahydropyridine-2- boronic acid pinacol esters
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A study on the conversion of lactam-derived vinyl triflates and phosphates into the corresponding vinyl boronates was carried out. While δ-valerolactam-derived vinyl triflates were successfully converted into 1,4,5,6-tetrahydropyridine-2-boronic acid pinacol ester derivatives by Pd-catalyzed coupling reaction with both bis(pinacolato)diboron and pinacolborane, pyrrolidinone and ε-caprolactam derivatives either did not react or were readily reduced. The δ-valerolactam-derived vinyl boronates are thermally stable compounds that efficiently coupled, under Pd catalysis, with structurally diverse aryl and heteroaryl bromides and triflates, vinyl iodides and bromides, and aromatic acid chlorides, to give the corresponding 2-substituted piperidines in good to excellent yields. The number of electrophiles that can virtually be coupled with these new boronic esters makes them very useful reagents for the synthesis of N-heterocyclic compounds.
- Occhiato, Ernesto G.,Lo Galbo, Fabrizio,Guarna, Antonio
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p. 7324 - 7330
(2007/10/03)
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- One-pot synthesis of cyclic enecarbamates from lactam carbamates
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A general, practical and efficient one-pot synthesis of cyclic enecarbamates is described. The protocol proceeds via reduction of lactam carbamate with Super-Hydride, followed by in situ dehydration with trifluoroacetic anhydride (TFAA) and diisopropylethylamine (DIPEA).
- Yu, Jurong,Truc, Vu,Riebel, Peter,Hierl, Elizabeth,Mudryk, Boguslaw
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p. 4011 - 4013
(2007/10/03)
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- Enantioselective syntheses of 2-alkyl- and 2,6-dialkylpiperidine alkaloids: preparations of the hydrochlorides of (-)-coniine, (-)-solenopsin A, and (-)-dihydropinidine.
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[reaction: see text] Sequences of lithiation-substitution, enantioselective hydrogenation, and diastereoselective lithiation-substitution provide efficient highly enantioselective syntheses of 2-substituted and cis and trans 2,6-disubstituted piperidines.
- Wilkinson,Stehle,Beak
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p. 155 - 158
(2007/10/03)
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- Efficient and Expeditious Protocols for the Synthesis of Racemic and Enantiomerically Pure Endocyclic Enecarbamates from N-Acyl Lactams and N-Acyl Pyrrolidines
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A mild, practical, and straightforward protocol for the construction of endocyclic enecarbamates starting from N-acyl lactams and N-acyl pyrrolidines is presented. Lactams were reduced to the corresponding α-hydroxycarbamates in good to excellent yields using DIBAL-H, SuperHydride, or NaBH4 followed by β-elimination (dehydration) promoted by trifluoroacetic anhydride in the presence of hindered nitrogenated bases such as 2,6-lutidine, diisopropylethylamine, or triethylamine. Small variations of this protocol permitted the preparation of several endocyclic enecarbamates (12 examples) in good to excellent overall yields (56-96%). The protocol was demonstrated to be applicable to several ring sizes, compatible with different protecting groups, and to be mild enough to prevent racemization of racemization-prone stereocenters. The efficacy of the procedure in the preparation of enantiomerically pure endocyclic enecarbamates was also demonstrated and compared to the commonly used Shono's protocol, which in our hands led to partial racemization of the endocyclic enecarbamate 18c.
- Oliveira, Denilson F.,Miranda, Paulo C. M. L.,Correia, Carlos R. D.
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p. 6646 - 6652
(2007/10/03)
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- Group VI metal-promoted endo-azacyclizations via alkyne-derived metal vinylidene carbenes
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The molybdenum-promoted cycloisomerization of terminal alkynes tethered to nitrogen nucleophiles is described. Reaction of N-carbamoyl alkynylamines with (Et3N)Mo(CO)5 affords cyclic enecarbamates. Similarly, cyclization of 2-ethynylaniline gives the isomeric indole heterocycle, although N-3- butynylaniline affords the cyclic metal azacarbene product.
- McDonald, Frank E.,Chatterjee, Arnab K.
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p. 7687 - 7690
(2007/10/03)
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- α-Lithioamine Synthetic Equivalents: Synthesis of Diastereoisomers from Boc Derivatives of Cyclic Amines
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Sequences of α'-lithiations and electrophilic substitutions of Boc-pyrrolidines, Boc-piperidines, and Boc-hexahydroazepines that provide compounds which are substituted adjacent to nitrigen are reported, and the pathways of the reactions are discussed.By this methodology monosubstituted 2 and disubstituted 2,4, 2,6, and 2,5 Boc-piperidines are obtained as single or separable diastereoisomers consistent with equatorial lithiations and retentive electrophilic substitution in chair conformations.Both cis and trans 2,6-disubstituted diastereoisomers can be prepared, and control of diastereoselectivity is demonstrated by syntheses of solenopsin A, a 2,6-trans-disubstituted piperidine, and of Boc-dihydropinidine, a 2,6-cis-disubstituted piperidine.In the case of 3-methoxy-Boc-piperidine elimination of methoxide occurs upon lithiation, and with cis-2,4-disubstituted Boc-piperidines the electrophile is introduced with trans stereochemistry at C-6.These reactions are suggested to involve twist boat conformations consistent with an X-ray crystal structure of 2-methyl-6-(trimethylstannyl)-4-phenyl-N-Boc-piperidine.Boc-pyrrolidine lithiates more rapidly than Boc-piperidine, provides 2-substituted products with electrophiles, and on further lithiation-substitution gives 2,5-cis- and -trans substituted products.Boc-perhydroazepine provides 2-substituted products by the sequence and on further lithiation-substitution gives 2,7-trans-disubstituted products.
- Beak, Peter,Lee, Won Koo
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p. 1109 - 1117
(2007/10/02)
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- REGIOSELECTIVE INTRODUCTION OF ALKYL GROUPS TO THE POSITION α OR γ TO NITROGEN ATOM OF PIPERIDINE SKELETONS USING ANODIC OXIDATION IN A KEY STEP
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β,γ-Unsaturated N-alkoxycarbonyl-α-methoxypiperidines, which were prepared from N-alkoxypiperidines by using anodic oxidation in a key step, were regioselectively alkylated at the α-position by using Grignard reagents in the presence of BF3*Et2O, whereas in the presence of CuBr, the alkylation took place at the γ-position.
- Shono, Tatsuya,Terauchi, Jun,Ohki, Yoshihisa,Matsumura, Yoshihiro
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p. 6385 - 6386
(2007/10/02)
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