共查询到20条相似文献,搜索用时 15 毫秒
1.
An asymmetric synthesis of (S)-oxybutynin 1 is described using the Sharpless asymmetric dihydroxylation of α-cyclohexylstyrene as the key step. 相似文献
2.
Subhash P. Chavan Nilesh B. DumareKishor R. Harale Uttam R. Kalkote 《Tetrahedron letters》2011,52(3):404-406
A synthetic route to (2S,3S)-3-hydroxypipecolic acid was achieved from readily available nonchiral pool starting material cis-2-butene-1,4-diol and involved Claisen orthoester rearrangement, Sharpless asymmetric dihydroxylation and intramolecular lactamisation of azido lactone as the key steps. 相似文献
3.
In Su Kim 《Tetrahedron letters》2006,47(41):7289-7293
An efficient stereoselective syntheses of (2S,3S)-3-hydroxypipecolic acid and (2R,3S)-2-hydroxymethylpiperidin-3-ol were achieved from p-anisaldehyde via the regioselective and diastereoselective introduction of an N-protected amine group using chlorosulfonyl isocyanate, ring-closing methathesis, and oxidation of p-methoxyphenyl group as the key steps. 相似文献
4.
Anubha Sharma 《Tetrahedron letters》2007,48(4):633-634
Two efficient asymmetric syntheses of (2S,3S)-safingol have been developed starting from easily available (R)-cyclohexylideneglyceraldehyde. The key steps in the syntheses were a diastereoselective addition of a suitable alkylmagnesium or lithium reagent, and simple organic transformations. Compared to earlier syntheses, the route involving alkyllithium addition is more viable practically due to its excellent diastereoselectivity, use of inexpensive materials/reagents and operational simplicity. 相似文献
5.
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
6.
Mandar S Bodas 《Tetrahedron letters》2004,45(5):987-988
A concise enantioselective synthesis of N-Boc-(2S,3S)-3-hydroxy-2-phenylpiperidine 1 is described starting from l-phenyl-glycine and using a Grignard reaction as a key step. 相似文献
7.
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
8.
Kim L. Curtis 《Tetrahedron letters》2005,46(32):5297-5300
The novel (2S,3S,4R)-3-amino-2-hydroxymethyl-4-hydroxypyrrolidine 5 has been produced in an efficient synthesis from trans-4-hydroxy-l-proline 8. The key step involves a tethered aminohydroxylation of the alkene 7 to introduce regio- and stereoselectively the amino alcohol functionality in the resulting products 6 and 13. Subsequent deprotection steps furnish the target molecule 5 as well as several differentially protected analogues. 相似文献
9.
An innovative and facile synthesis of the title compound has been developed starting from (R)-cyclohexylidene glyceraldehyde. The key step in the synthesis is a chiral template-driven Grignard addition with absolute diastereocontrol. The other attractive features are the operational simplicity and the use of inexpensive compounds/reagents. 相似文献
10.
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
11.
Marie-Priscille BrunAnne-Sophie Martin Christiane Garbay Laurent Bischoff 《Tetrahedron letters》2003,44(37):7011-7013
The synthesis of (2S,5R)-5-ethoxycarbonylmethyl-pyrrolidine-2-carboxylic acid was achieved in two steps, with an overall yield of 53%. This synthesis used Cbz-Glu-OBzl as the starting material and led to the titled compound with a d.e.>96%. 相似文献
12.
A brief and facile synthesis of the title compounds has been developed by using an efficient lipase-catalyzed acylation and a chiral template-directed diastereoselective alkylation for incorporating the stereogenic centres. A cross-metathesis was employed to get the required E-olefin geometry. 相似文献
13.
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
14.
Paulo H.G. Zarbin Alfredo R.M. de OliveiraCarlos E. Delay 《Tetrahedron letters》2003,44(36):6849-6851
A diastereoselective approach to (2R,5S)- and (2S,5S)-2-methyl-1,6-dioxaspiro[4.5]decane 1 and 1a is described. The route starts with an alkylation reaction among the cyclopentanone N,N-dimethylhydrazone 6 and the chiral iodides (R)-3 or (S)-3, derived from the enantiomers of ethyl β-hydroxybutyrate, controlling the estereocenter at C-2 of the molecules. The alkylated products 7 and 7a were easily transformed into the 1,8-O-TBS-1,8-dihydroxy-5-nonanones 9 and 9a in four steps, and a subsequent stereoselective spiroketalization, in acidic media, afforded a Z:E mixture (1:2) of compounds 1 and 1a. 相似文献
15.
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
16.
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
17.
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
18.
The synthesis is described of the two enantiomerically pure isomers (+)-(3S,7S,10S)- and (+)-(3S,7S,10R)-3,7,10-trimethylboratr The structures were determined by 1H- and 13C-NMR spectroscopy. A method for increasing the enantiomeric purity by trimerization reactions of partially-resolved (S) propylene oxide is proposed. The reaction was studied from the kinetic viewpoint and interpreted according to a binomial probability scheme. The experimental findings point to a rapid growth in enantiomeric purity for the (SSS) trimer compared with the starting material, whilst no increase was found for the (SSR) trimer. 相似文献
19.
Pravin L. Kotian 《Tetrahedron letters》2005,46(19):3327-3330
A concise stereoselective synthesis of an imino sugar, (3S,4R)-4-(hydroxymethyl)pyrrolidin-3-ol from (S)-diethylmalate has been developed in five steps and in overall yield of 28%. 相似文献
20.
Maddimsetti Venkateswara RaoKotha kapu Sridhar Reddy Batchu Venkateswara Rao 《Tetrahedron letters》2012,53(45):5993-5995
An efficient strategy has been developed for the stereo selective synthesis of N-Boc-(2S,3S)-3-hydroxy-2-phenyl piperidine and N-Boc-safingol from benzaldehyde and N-Boc-imine. 相似文献