- Decarboxylative Conjunctive Cross-coupling of Vinyl Boronic Esters using Metallaphotoredox Catalysis
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The synthesis of complex alkyl boronic esters through conjunctive cross-coupling of vinyl boronic esters with carboxylic acids and aryl iodides is described. The reaction proceeds under mild metallaphotoredox conditions and involves an unprecedented decarboxylative radical addition/cross-coupling cascade of vinyl boronic esters. Excellent functional-group tolerance is displayed, and application of a range of carboxylic acids, including secondary α-amino acids, and aryl iodides provides efficient access to highly functionalized alkyl boronic esters. The decarboxylative conjunctive cross-coupling was also applied to the synthesis of sedum alkaloids.
- Aggarwal, Varinder K.,Duong, Vincent K.,Mega, Riccardo S.,Noble, Adam
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supporting information
p. 4375 - 4379
(2020/02/11)
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- A rapid access to (±)-sedamine and some original N -benzyl unsaturated analogues
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Reduction of N-alkyl-2-(2-hydroxy-2-phenylethyl)pyridinium salts using excess of sodium triacetoxyborohydride afforded exclusively the corresponding tetrahydropyridine derivative bearing a piperidine ring with a double bond in the 3,4-position. Furthermore, under these conditions, syn-1,3-amino alcohols were obtained in good yield and diastereoselectivity. Georg Thieme Verlag Stuttgart · New York.
- Boussonniere, Anne,Ranaivondrambola, Tsiresy,Lebreton, Jacques,Mathe-Allainmat, Monique
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experimental part
p. 2456 - 2462
(2010/09/04)
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- Hydroformylation of homoallylic azides: A rapid approach toward alkaloids
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(Chemical Equation Presented) Unprecedented hydroformylation of homoallylic azides combined with useful one-pot operations provides an expeditive access to alkaloids.
- Spangenberg, Thomas,Breit, Bernhard,Mann, Andre
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supporting information; experimental part
p. 261 - 264
(2009/08/08)
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- Enantioselective synthesis of lobeline via nonenzymatic desymmetrization
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Lobeline has been prepared in enantiopure form via desymmetrization of lobelanidine with use of BTM, a nonenzymatic enantioselective acyl transfer catalyst.
- Birman, Vladimir B.,Jiang, Hui,Li, Ximin
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p. 3237 - 3240
(2008/02/11)
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- An efficient approach to 2-substituted N-tosylpiperdines: asymmetric synthesis of 2-(2-hydroxy substituted)piperidine alkaloids
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We have developed an efficient and a general approach to chiral 2-substituted N-tosylpiperidines starting from chiral α-substituted-N-tosylaziridines. Using this approach, we have synthesized (+)-coniine. The synthesis of chiral N-tosyl-2-piperidinylethanol 15 and ent-15, was achieved from l- and d-aspartic acids, respectively in few steps. Piperidine 15 was converted into 2-(2-hydroxysubstituted)piperidines of type 2 in optically active form. By applying this strategy, asymmetric syntheses of halosaline (R,R)-2a, (+)- and (-)-sedamine 2b, (+)- and (-)-allosedamine 2c, (+)- and (-)-sedridine 2d, (+)- and (-)-allosedridine 2e, (+)-tetraponerine T-3 3a, T-4 3c, T-7 3b, and T-8 3d have been achieved in high yields. These stereoisomers can be interconverted via Mitsunobu inversion in excellent yields.
- Bisai, Alakesh,Singh, Vinod K.
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p. 1907 - 1910
(2007/10/03)
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- Enantioselective synthesis of (+)-sedamine and (-)-allosedamine
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Two different approaches to the enantioselective syntheses of (+)-sedamine and (-)-allosedamine are described, both using the Sharpless asymmetric epoxidation as the key step. Regioselective reduction of epoxides, chemoselective oxidation of alcohols, ring-closing metathesis, and nucleophilic displacements were the other key steps employed. Georg Thieme Verlag Stuttgart.
- Yadav,Reddy, M. Sridhar,Rao, P. Purushothama,Prasad
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p. 4005 - 4012
(2008/03/11)
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- Stereoselective synthesis of (-)-allosedamine and (1R,3R)-HPA-12 from β-p-toluenesulfonamido-γ,δ-unsaturated sulfoxide
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A stereoselective synthesis of (-)-allosedamine and HPA-12 is disclosed. The key steps of the synthesis include the diastereoselective synthesis of a β-sulfonamido unsaturated sulfoxide, elaboration of a bromohydrin via intramolecular sulfinyl group participation and a ring-closing metathesis reaction for the construction of the piperidine ring of allosedamine.
- Raghavan, Sadagopan,Rajender
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p. 5059 - 5067
(2007/10/03)
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- Stereoselective synthesis of (-)-allosedamine
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A stereoselective synthesis of (-)-allosedamine is disclosed. β-Aminosulfoxide 4 was generated stereoselectively by condensation of the sulfinyl anion 2 with N-Ts imine 3. The bromohydrin 5 was obtained by intramolecular sulfinyl group participation and the piperidine ring of allosedamine was elaborated using the ring-closing metathesis (RCM) reaction.
- Raghavan, Sadagopan,Rajender
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p. 1919 - 1922
(2007/10/03)
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- Remote Stereocenter Discrimination in the Enzymatic Resolution of Piperidine-2-ethanol. Short Enantioselective Synthesis of Sedamine and Allosedamine
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Kinetic resolution of N-Boc-piperidine-2-ethanol (2), a case of remote stereocenter discrimination, was accomplished by sequential transesterification mediated by two enzymes, Lipase PS and porcine pancreatic lipase, showing opposite enantioselectivity. The gram-scale availability of the two enantiomeric N-Boc alcohols 2a (R) and 2c (S) enlarges their synthetic exploitation for the enantioselective preparation of piperidine alkaloids. As an example, the convenient three-step synthesis of both the enantiomers of sedamine and allosedamine is described.
- Angoli, Marco,Barilli, Alessio,Lesma, Giordano,Passarella, Daniele,Riva, Sergio,Silvani, Alessandra,Danieli, Bruno
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p. 9525 - 9527
(2007/10/03)
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- Enantiospecific and stereoselective synthesis of (-)-allosedamine
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A total synthesis of (-)-allosedamine (>99% ee, de) is described in 14 steps with an overall yield of 29% from benzaldehyde.
- Felpin, Fran?ois-Xavier,Lebreton, Jacques
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p. 225 - 227
(2007/10/03)
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- A concise synthesis of homochiral sedamines and related alkaloids. A new reductive application of Jacobsen's catalyst
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Two methods for the generation of both enantiomers of sedamine [1- methyl-2-(2-phenyl-2-hydroxy-1-ethyl)piperidine] in high optical purity have been elaborated. The first utilises the lipase-mediated kinetic resolution of racemic acetates and the second involves the NaBH4 mediated reduction of ketones catalysed by Jacobsen's catalyst. Some related applications of these reactions are also disclosed.
- Yu, Chu-Yi,Meth-Cohn, Otto
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p. 6665 - 6668
(2007/10/03)
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- An applied stereocontrolled synthesis of piperidine derivative utilizing diastereoselective reaction of chiral 1,3-oxazolidine with grignard reagent; Asymmetric synthesis of an alkaloid, (-) sed amine
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A facile total synthesis of enantiomerically pure (-)-sedamine, known as a naturally occurring alkaloid, was accomplished by use of the diastereo-selective addition of Grignard reagent to a chiral 1,3-oxazolidine, and utilizing of 1-aza-4-oxabicyclo[4.3.0
- Poerwono, Hadi,Higashiyama, Kimio,Takahashi, Hiroshi
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p. 263 - 270
(2007/10/03)
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- Diastereo- and enantiocontrolled synthesis of (-)-allosedamine via cycloaddition of a chiral nitrone
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The piperidine alkaloid (-)-allosedamine (1) has been synthesized, in 21% overall yield, in nine steps starting from the formyl-ester 4. The synthesis features the reaction cascade 7 → 3 → 2, involving asymmetric electrophilic enolate hydroxyamination, hy
- Oppolzer,Tamura,Deerburg
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p. 554 - 560
(2007/10/02)
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- A FACILE SYNTHESIS OF dl-SEDAMINE AND dl-ALLOSEDAMINE
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Racemic sedamine and dl-allosedamine were easily synthesized from the intermediate (3) using a cyclic acyliminium salt by the addition-elimination reaction sequence.
- Ozawa, Naganori,Nakajima, Setsuko,Zaoya, Kyoko,Hamaguchi, Fumiko,Nagasaka, Tatsuo
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p. 889 - 894
(2007/10/02)
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- Trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed amidoalkylation of silylenolethers. Stereocontrolled syntheses of (+/-)-sedamine and (+/-)-norsedamine
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Trimethylsilyl trifluoromethanesulfonate (TMSOTf) catalyzed addition of 1-trimethylsilyloxy-1-phenylethene to N-ethoxycarbonyl- and N-tert-butoxycarbonyl-2-ethoxypiperidines (3a and 3b, respectively) afforded the corresponding ketocarbamates 4a and 4b, in excellent yields. Stereoselective conversion to (±)-norsedamine (7) and (±)-sedamine (8) is described.
- Pilli,Dias
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p. 2213 - 2229
(2007/10/02)
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- Stereochemistry of the Intermolecular and Intramolecular Conjugate Additions of Amines and Anions to Chiral (E)- and (Z)-Vinyl Sulfoxides. Total Syntheses of (R)-(+)-Carnegine and (+)- and (-)-Sedamine
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The intramolecular addition of incipient amine anions to chiral (E)- and (Z)-vinyl sulfoxides occurs in the same diastereofacial sense, giving chiral isoquinoline and piperidine derivatives that differ in relative stereochemistry at C-2.In contrast, the conjugate addition reactions of (E)- and (Z)-β-styryl p-tolyl sulfoxide wih benzylamine and LiCH(CO2Et)2 are diastereoconvergent processes.The same major diastereomeric product is obtained in each case.We have attempted to rationalize the stereochemical outcome of the addition of nucleophiles to chiral vinyl sulfoxides according to the type of nucleophilic reagent employed (either chelating/hydrogen bonding or nonchelating) and from a consideration of possible transition states.
- Pyne, Stephen G.,Bloem, Peter,Chapman, Sandra L.,Dixon, Christine E.,Griffith, Renate
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p. 1086 - 1093
(2007/10/02)
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- ASYMMETRIC SYNTHESIS OF (+)- AND (-)-CONIINES AND (-)-SEDAMINE BY DIASTEREOSELECTIVE ALKYLATION REACTION OF ETHOXYPIPERIDININE
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Diastereoselective alkylation reaction of the chiral 6-ethoxypiperidinones (4) and (5) has been developed and successfully applied to the asymmetric synthesis of piperidine alkaloids, (+)- and (-)-coiines (11) and (12), (-)-sedamine (21), and (-)-allosedamine (22).
- Kiguchi, Toshiko,Nakazono, Yoko,Kotera, Sanae,Ninomiya, Ichiya,Naito, Takeaki
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p. 1525 - 1535
(2007/10/02)
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- THE CYCLOADDITION REACTION BETWEEN STYRENE AND 2,3,4,5-TETRAHYDROPYRIDINE 1-OXIDE
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The cycloaddition of styrene to 2,3,4,5-tetrahydropyridine 1-oxide leads, with a high yield, to a 97:3 mixture of the diastereoisomeric isoxazolidines 3c and 4c respectively.
- Hootele, C.,Ibebeke-Bomangwa, W.,Driessens, F.,Sabil, S.
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