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1.
Philippe Bisel 《Tetrahedron》2004,60(46):10541-10545
Asymmetric synthesis of (1R,2S)- and (1S,2R)-1-amino-cis-3-azabicyclo[4.4.0]decan-2,4-diones has been achieved. The underlying second generation asymmetric synthesis proceeds via a Strecker reaction with commercially available (R)-1-phenylethylamine (1-PEA) as chiral auxiliary, TMSCN as cyanide source and racemic ethyl 2-(2-oxocyclohex-1-yl)ethanoate. A ring closure addition-elimination reaction between an amide nitrogen and the ester functionality leads to the 1-amino-3-azabicyclo[4.4.0]decan-2,4-diones. The absolute configurations of the title compounds have been assigned based on detailed NMR-spectroscopic analysis and X-ray data. 相似文献
2.
Kosuke Okuma Akira M. Ono Makoto Oba Masatsune Kainosho Tsutomu Terauchi 《Tetrahedron letters》2009,50(13):1482-163
We have developed a synthetic route for (2S,3R)- and (2S,3S)-[2-13C;3-2H] glutamic acids with high enantioselectivity. The key reactions in this synthesis are the asymmetric reduction of the 2,3-didehydroornithine derivative using the (S,S)-Et-DuPHOS-Rh catalyst and the oxidation of the δ-position by ruthenium catalysis. 相似文献
3.
Michail N. Elinson Sergey K. Feducovich Anatolii N. Vereshchagin 《Tetrahedron》2004,60(51):11743-11749
Electrolysis of arylidenemalononitriles and malononitrile in alcohols in an undivided cell in the presence of sodium bromide as mediator results in the stereoselective formation of (1R,2S,6R)*-6-aryl-2-amino-4,4-dialkoxy-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-enes in 60-80% yields. 相似文献
4.
Michail N. Elinson Sergey K. Feducovich Anatolii N. Vereshchagin Gennady I. Nikishin 《Tetrahedron letters》2005,46(37):6389-6393
Electrolysis of arylidene- or alkylidenemalononitriles and malonate in alcohol in an undivided cell in the presence of sodium halide as mediator results in the stereoselective formation of alkyl (1R,5R,6R)* 6-substituted 5-cyano-4,4-dialkoxy-2-oxo-3-azabicyclo[3.1.0]hexan-1-carboxylates in 50-70% yields. 相似文献
5.
The efficient synthesis of four benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-ω-iodoalkanoates {benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-3-iodopropanoate, benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-4-iodobutanoate, benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-5-iodopentanoate, benzyl 2-(S)-[(tert-butoxycarbonyl)amino]-6-iodohexanoate} from natural or protected l-amino acids is described. 相似文献
6.
Jayant N TilekarNitin T Patil Harishchandra S JadhavDilip D Dhavale 《Tetrahedron》2003,59(11):1873-1876
The syntheses of (2S,3R,4R,5R) and (2S,3R,4R,5S)-1,6-dideoxy-1,6 iminosugars 1a and 1b, respectively, from d-glucose are described. The key transformations in this reaction sequence include regio-selective epoxide ring opening with N-benzylamine followed by intramolecular reductive amination of amino-aldehyde. 相似文献
7.
Christine Gauzy 《Tetrahedron letters》2004,45(38):7095-7097
(+)-(1S,2R) and (−)-(1R,2S)-2-aminocyclobutane-1-carboxylic acids have been prepared in >97% ee and in 33% and 20% overall yields starting from a single, chiral, bicyclic compound perceived as a chiral uracil equivalent. Construction of the cyclobutane ring is achieved via a [2+2] photocycloaddition reaction of this chiral precursor with ethylene. 相似文献
8.
Subhash P. Chavan Cherukupally Praveen Pallavi Sharma U.R. Kalkote 《Tetrahedron letters》2005,46(3):439-441
A short synthetic route to (−)-and (+)-bulgecinine, the amino acid moiety of the bulgecins was achieved from the readily available nonchiral pool starting material cis-2-butene-1,4-diol in which a Claisen orthoester rearrangement and a Sharpless asymmetric dihydroxylation were used as the key steps. 相似文献
9.
D. Gautam 《Tetrahedron letters》2010,51(32):4199-4201
A stereoselective approach for the synthesis of (+)-(1R,2S,5S,7R)-2-hydroxy-exo-brevicomin from l-ascorbic acid has been described. The key steps are highly stereoselective nucleophilic addition reaction on aldehyde 8 and also a single pot transformation of 15 to (+)-(1R,2S,5S,7R)-2-hydroxy-exo-brevicomin. The later tandem reaction which involves the hydrogenation of double bond, debenzylation, MOM deprotection and bicyclic ketal formation was carried under Pd/C, H2 followed by acid treatment. 相似文献
10.
A stereoselective synthesis of (2R,3R) and (2R,3S)-3-hydroxyleucine is disclosed. The key step of the reaction sequence involves, stereo- and regioselective bromohydration of 7, using a brominating agent derived in situ from N-bromosuccinimide and 2,6-lutidine, via intramolecular sulfinyl group participation. 相似文献
11.
Barbara Szechner 《Tetrahedron》1981,37(5):949-952
The synthesis of (1R, 2S, 3R) and (1S, 2S, 3R)-2-(N-benzoylamino)-1-(2-furyl)-1, 3-butandiols (15) and (16) from D-threonine is described. The assignment of absolute configuration of the newly formed asymmetric center at C-1 was based on the 1H-NMR spectra of O-isopropylidene derivatives 17 and 18. 相似文献
12.
Zi-Qiang GuMin Li 《Tetrahedron letters》2003,44(15):3203-3205
A concise, multi-gram scale method for producing the bioactive and enantiomerically pure epimers, (2S,4R)- and (2S,4S)-glutamic acids, in a single synthetic scheme is described. 相似文献
13.
Diastereoselective synthesis of (R,R/S,S)-2-[2-(2-aryl)-1-phenyl-ethyl]-morpholines 6 has been achieved through the preparation of key E-enol-triflate 4 and its further coupling with benzylzinc reagents and final hydrogenation. 相似文献
14.
The total synthesis of an alkylcitrate secondary metabolite from the fungi Trichoderma viride is described. An ester dienolate [2,3]-Wittig rearrangement and a S. Julia-Kocienski olefination served as key C/C-connecting transformations. The highly convergent synthesis consists of a longest linear sequence of 17 steps. 相似文献
15.
Methyl (1S,2R,4S,5R)-7-aza-5-bromo-bicyclo[2.2.1]heptane-2-carboxylate was synthesized in high yield in short time from methyl (1R,2S,4R,5R)-2-amino-4,5-dibromocyclohexanecarboxylate through intramolecular cycloamination under microwave-assisted conditions. The following substitution reaction by trifluoro-acetate anion also took place in microwave-assisted conditions to afford methyl (1S,2R,4S,5S)-7-aza-5-hydroxy-bicyclo[2.2.1]heptane-2-carboxylate. In the acyloxylation reaction, unusual endo-selectivity was observed owing to 7-azabicyclo[2.2.1]heptane skeleton. 相似文献
16.
Nilesh M. Shirode 《Tetrahedron》2006,62(18):4615-4621
An efficient synthesis of 3-amino-2-hydroxydecanoic acid (AHDA), a nonproteinogenic amino acid, using enantiopure 3-benzyloxy-4-formylazetidin-2-one as a building block is described. Both the enantiomers of AHDA have been synthesized from the corresponding enantiomer of 3-benzyloxy-4-formylazetidin-2-one in good yield and optical purity. 相似文献
17.
Jean Quancard 《Tetrahedron letters》2004,45(10):2185-2187
The synthesis of 3-benzylprolines can be easily achieved in a diastereoselective and enantioselective way via amino-zinc-ene-enolate cyclisation. Transmetalation of the cyclic zinc intermediate with Pd2(dba)3/P(o-Tolyl)3 allowed functionalisation with an aromatic ring. One-pot hydrogenolysis and Boc-protection led to the cis-isomer readily usable for peptide synthesis. The trans-isomer was obtained by epimerisation of the α-centre in a sealed tube at 200 °C. 相似文献
18.
Facile chemoenzymatic enantioselective synthesis of (3S,4S)-3-methoxy-4-methylaminopyrrolidine, a key intermediate for a new quinolone antitumor compound AG-7352 has been described. This methodology illustrates the preparation of 3-azido-1-benzyloxycarbonyl-4-hydroxypyrrolidine starting from diallylamine via 1-benzyloxycarbonyl-3-pyrroline obtained by ring-closing metathesis (RCM) employing Grubbs’ catalyst. Enzymatic transesterification employing PS-C lipase gave (3S,4S)-3-azido-1-benzyloxycarbonyl-4-hydroxypyrrolidine in >99% ee, which upon methylation of the hydroxyl group followed by sequential reactions gave the desired intermediates, (3S,4S)-1-tert-butoxycarbonyl-3-tert-butoxycarbonylamino-4-methoxypyrrolidine. 相似文献
19.
Alaa A.-M. Abdel-Aziz Serry A.A. El Bialy Takehisa Kunieda 《Tetrahedron letters》2004,45(43):8073-8077
An enantioselective synthesis of sterically congested 1,2-di-tert-butyl and 1,2-di-(1-adamantyl)ethylenediamines has been developed. Thus, diastereomerically pure trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully prepared by optical resolution of (±)-trans-4,5-dimethoxy-2-imidazolidinone using apocamphanecarbonyl chloride (MAC-Cl) followed by stereospecific and stepwise substitution of the dimethoxyl groups using tert-butyl or 1-adamantyl cuprates to provide (4S,5S)-4,5-di-tert-butyl and (4R,5R)-4,5-di-(1-adamantyl)-2-imidazolidinones 12 and 15, respectively. Furthermore, N-acetyl 4,5-di-tert-butyl and 4,5-di-(1-adamantyl)-2-imidazolidinones 16a,b were enantioselectively deacetylated using a catalytic oxazaborolidine system to provide enantiopure 1-p-tolylsulfonyl-4,5-di-tert-butyl-2-imidazolidinones 12 and 19 and 1-p-tolylsulfonyl-4,5-di-(1-adamantyl)-2-imidazolidinones 18 and 20, respectively. Finally, N-p-tolylsulfonyl-2-imidazolidinones 12 and 15 were treated with 30 equiv of Ba(OH)2·8H2O to achieve ring cleavage and to provide (1S,2S)-1,2-di-tert-butylethylenediamine 3 and (1R,2R)-1,2-di-(1-adamantyl)ethylenediamine 4. 相似文献
20.
Anna Trifonova 《Tetrahedron》2004,60(15):3393-3403
New 2-aza-norbornane-oxazoline compounds were synthesized and evaluated as ligands in the transfer hydrogenation of acetophenone. The best catalyst prepared in situ from [IrCl2(COD)]2 and a ligand afforded 1-(S)-phenylethanol in good yields and 79% ee. 相似文献