共查询到20条相似文献,搜索用时 15 毫秒
1.
An efficient enantiospecific synthesis of R(+)-α-Lipoic acid (1) a prosthetic group and a vital cofactor in -α-keto acids decarboxylation is described. 相似文献
2.
《Tetrahedron: Asymmetry》1998,9(23):4113-4115
A short, efficient synthesis of (R)-3-hydroxytetradecanoic acid, a key component of bacterial endotoxins, using (R)-oxirane acetic acid ethyl ester as the source of chirality is described. The method is general and can be used in the preparation of other chiral 3-hydroxy acids. 相似文献
3.
Concise and efficient asymmetric total syntheses of (+)-strictifolione 1 and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one 2 have been achieved based on the strategic application of one-pot double allylboration and ring-closing metathesis reactions. The total syntheses proceeded in only five and seven steps, respectively, from readily available 3-butenal and represent the shortest syntheses of 1 and 2 reported to date. 相似文献
4.
A short and efficient synthesis of the commercially unavailable (R)-(+) isomer of perillaldehyde from (+)-limonene oxide has been developed. 相似文献
5.
《Tetrahedron: Asymmetry》2006,17(18):2632-2636
A short and efficient synthesis of (R)-(−)-sporochnol A in five steps and 9% overall yield has been developed. The sequence uses as starting material the easily available enantiopure monoketal derived from 1,4-cyclohexanedione and (R,R)-hydrobenzoin that serves as a chiral auxiliary. 相似文献
6.
Daniel Obrecht Helena Karajiannis Christian Lehmann Peter Schnholzer Clive Spiegler Klaus Müller 《Helvetica chimica acta》1995,78(3):703-714
An efficient synthesis of enantiomerically pure (R)- and (S)-2-(aminomethyl)alanine ((R)- and (S)-Ama) 1a and (R)- and (S)-2-(aminomethyl)leucine ((R)- and (S)-Aml) 1b is described (Schemes 1 and 2). Resolution of the racemic amino acids was achieved using L -phenylalanine cyclohexylamide ( 2 ) as chiral auxiliary. The free amino acids 1a, b were converted to the Nα-Boc,Nγ-Z-protected derivatives 11a, b (Scheme 3) ready for incorporation into peptides. Based on the three crystal structures of the diastereoisomeric peptides 8a, 8b , and 9b , the absolute configurations in both series were determined. β-Turn type-I geometries were observed for structures 8b and 9b , whereas 8a crystallized in an extended backbone conformation. 相似文献
7.
Here we present new routes for the efficient syntheses of 6,5'-(S)- and 6,5'-(R)-cyclouridine. The syntheses utilize readily accessible uridine as a starting material. This route to the R diastereomer is significantly more efficient than previous synthetic efforts, allowing us to obtain large amounts of pure material for future biological testing. 相似文献
8.
I. V. Mineeva 《Russian Journal of Organic Chemistry》2013,49(2):253-258
A simple and efficient asymmetrical synthesis was performed of a convenient bifunctional building block, methyl (R)-5,5-dimethoxy-3-methylpentanoate and its (S)-enantiomer. The possibility was shown of its application to the synthesis of insect pheromones. 相似文献
9.
Jürgen Brem Csaba Paizs Monica Ioana Toşa Elemér Vass Florin Dan Irimie 《Tetrahedron: Asymmetry》2009,20(4):489-496
Starting from the racemic 3-benzofuranyl- and 3-benzo[b]thiophenyl-3-hydroxypropanoic acid ethyl esters as substrates, various multistep enzymatic procedures were developed for the efficient synthesis of the corresponding highly enantiomerically enriched (R)- and (S)-3-heteroaryl-3-hydroxypropanoic acids. 相似文献
10.
Efficient and practical synthesis of (R)-2-methylpyrrolidine 总被引:1,自引:0,他引:1
Zhao D Kuethe JT Journet M Peng Z Humphrey GR 《The Journal of organic chemistry》2006,71(11):4336-4338
An efficient, practical, and high yielding synthesis of (R)-2-methylpyrrolidine is described. The sequence allows for the scalable preparation of the target compound in just four synthetic steps and proceeds in 83% overall yield and >99% optical purity from readily available starting materials. 相似文献
11.
12.
Lall MS Hoge G Tran TP Kissel W Murphy ST Taylor C Hutchings K Samas B Ellsworth EL Curran T Showalter HD 《The Journal of organic chemistry》2012,77(10):4732-4739
(S)-3-(methylamino)-3-((R)-pyrrolidin-3-yl)propanenitrile (1) is a key intermediate in the preparation of PF-00951966, (1) a fluoroquinolone antibiotic for use against key pathogens causing community-acquired respiratory tract infections including multidrug resistant (MDR) organisms. The current work describes the development of a highly efficient and stereoselective synthesis of 1 in 10 steps with an overall yield of 24% from readily available benzyloxyacetyl chloride. Two key transformations in the synthetic sequence involve (a) catalytic asymmetric hydrogenation with chiral DM-SEGPHOS-Ru(II) complex to afford β-hydroxy amide 11b in good yield (73%) and high stereoselectivity (de 98%, ee >99%) after recrystallization and (b) S(N)2 substitution reaction with methylamine to provide diamine 14 with inversion of configuration at the 1'-position in high yield (80%), after efficient purification using a simple acid/base extraction protocol. 相似文献
13.
《Tetrahedron: Asymmetry》2000,11(20):4105-4111
The efficient preparation of enantiomerically pure (R)- and (S)-2-bromohexadecanoic acids with e.e.>95% through resolution with the use of a recoverable chiral auxiliary is described. The procedure involves three reactions: Steglich esterification, DIBAL reduction, and Sharpless oxidation. The assessment of the enantiomeric purity is based on NMR analysis by using (1R,2R)-(+)-diphenylethane-1,2-diamine as a chiral solvating agent. 相似文献
14.
Xu Qin Li Yun Xu Yang Wei Li Wang Bin Hu Hui Min Xue Tian Yi Zhang Xue Tao Zhang 《中国化学快报》2011,22(7):765-767
A practical chemical synthesis of L-carmtine(1) has been accomplished from(R)-3-chloro-1,2-propanediol((R)-4),which is a main by-product originated from(R,R)-Salen Co(Ⅲ) catalyzed hydrolytic kinetic resolution(HKR) of(±)-epichlorohydrin.(R)-4 was utilized as a chiral starting material to prepare the key intermediate cyclic sulfite((R)-S).The new synthetic approach demonstrated an efficient utilization of organic by-product for the asymmetric synthesis of bioactive compounds. 相似文献
15.
Jürgen Brem Monica Ioana Toşa Csaba Paizs Elemér Vass Florin Dan Irimie 《Tetrahedron: Asymmetry》2010,21(3):365-373
Starting from the racemic ethyl 3-hydroxy-3-(10-alkyl-10H-phenothiazin-3-yl)propanoates as substrates, a multienzymatic procedure was developed for the efficient synthesis of the corresponding highly enantiomerically enriched (R)- and (S)-3-heteroaryl-3-hydroxypropanoic acids. 相似文献
16.
An efficient stereoselective synthesis of fully protected (2S,4R)-4-methylpipecolic acid has been developed. The synthesis was achieved by initial asymmetric α-alkylation of glycine with a chiral iodide, affording the linear precursor as a single stereoisomer. Subsequent aldehyde formation using OsO(4)/NaIO(4) followed by immediate intramolecular cyclization afforded an enamine that was then subjected to hydrogenation to give the final compound in 23% yield over 10 steps. 相似文献
17.
《Tetrahedron: Asymmetry》2001,12(17):2421-2425
An efficient process for the synthesis of (R)-N-t-Boc-4-piperidinylglycine 8a, an unnatural amino acid, via enantioselective rhodium-catalyzed hydrogenation of the Cbz-enamide 5a is described. Subsequent deprotection of 8a affords unprotected (R)-4-piperidinylglycine 9 in good yield. 相似文献
18.
I. V. Mineeva 《Russian Journal of Organic Chemistry》2013,49(6):838-842
A simple and efficient asymmetric synthesis of (5S,7R)-7-hydroxydodecano-5-lactone, a component of the giant danaine butterfly Idea leuconoe pheromone, and formal syntheses of (+)-(3R,5R)-3-hydroxydecano-5-lactone, verbalactone, and Tolypothrix pentaether have been accomplished starting from methyl (3R,5R)-3,5-dihydroxydecanoate. The latter is obtained from methyl 3-[(tributylstannyl)methyl]but-3-enoate using Keck allylation in the key step of the construction of its carbon skeleton. 相似文献
19.
Davies SG Díez D El Hammouni MM Garner AC Garrido NM Long MJ Morrison RM Smith AD Sweet MJ Withey JM 《Chemical communications (Cambridge, England)》2003,(19):2410-2411
Comparison of the kinetic and parallel kinetic resolutions of methyl (RS)-5-tert-butyl-cyclopentene-1-carboxylate allows for the efficient synthesis of both (1R,2S,5S)- and (1S,2R,5R)-enantiomers of methyl 2-amino-5-tert-butyl-cyclopentane-1-carboxylate. 相似文献
20.
An efficient synthesis of (R)-7-(3-benzothienylamido)deacetoxy-cephalosporanic acid (1) is described beginning from (R)-alpha-aminobenzo[b]thiophene-3- acetic acid (2) and 7-amino-3-methyl-3-cephem-4-carboxylic acid (7-ADCA). Good yields were obtained and the procedure is amenable to multikilogram preparations. 相似文献