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1.
Meryem Fistikci Ozlem Gundogdu Derya Aktas Hasan Secen M. Fethi Sahin Ramazan Altundas Yunus Kara 《Tetrahedron》2012,68(12):2607-2610
A new synthetic strategy for (R)- and (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid, a building block in the preparation of sitagliptin and its derivatives, was developed. Pd(OAc)2 catalyzed coupling of 2,4,5-trifluoro-1-iodobenzene with allyl alcohol gave 3-(2,4,5-trifluorophenyl)propanal in a yield of 95%. l-Proline catalyzed reaction of the 3-phenylpropanal (in only 1.2 molar equiv) with nitrosobenzene followed by reduction with NaBH4 and Pd/C catalyzed hydrogenation gave (R)-3-(2,4,5-trifluorophenyl)propane-1,2-diol with >99% ee and 65% yield. Selective tosylation of primary hydroxyl group of the 1,2-propandiol unit followed by cyanide displacement afforded (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanenitrile (80%). The nitrile was converted to the title β-hydroxy acid under basic hydrolysis in a yield of 90%. Thus, (R)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid was prepared enantioselectively from the starting material in four steps and 45% overall yield. The reaction sequence was repeated with d-proline as the catalyst to give (S)-3-hydroxy-4-(2,4,5-trifluorophenyl)butanoic acid in 45% overall yield and >99% enantiomeric excess. 相似文献
2.
(4S, 5S)- and (4S, 5R)-5-Hydroxy-4-decanolide ( 1a and 1b ), the proposed autoregulators from Strepotomyces Griseus were synthesized from a propargyl alcohol 2 in an overall yield of 30%, employing the Sharpless asymmetric epoxidation as the key step. 相似文献
3.
Shana Sudhakaran Prasad G. Shinde Eswar K. Aratikatla Sandeep H. Kaulage Priksha Rana Ratan S. Parit Dattatry S. Kavale Beeran Senthilkumar Benudhar Punji 《化学:亚洲杂志》2022,17(1):e202101208
Nickel-catalyzed enantioselective hydrogenation of enamines leading to the efficient synthesis of 3-R-Boc-amino-4-(2,4,5-trifluorophenyl)butyric esters, the key intermediate of the blockbuster antidiabetic drug (R)-SITAGLIPTIN, is described. The sitagliptin motifs were isolated in more than 99% yield and with 75–92% ee using the earth-abundant nickel catalyst. Upon chiral resolution with (R)- and (S)-1-phenylethylamines, the partially enantioenriched (R)- and (S)-Boc-3-amino-4-(2,4,5-trifluorophenyl)butanoic acids provided >99.5% ee of the crucial sitagliptin intermediate. The asymmetric hydrogenation protocol was scaled up to 10 g with consistency in yield and ee, and has been reproduced in multiple batches. 相似文献
4.
The chiral epoxy alcohol 3 was synthesized in 92% e.e through the kinetic resolution of (±)-l-tridecen-3-ol 2 by Sharpless asymmetric epoxidation. 3 was then transformed to (7R, 8S)-1a, the sex pheromone of gypsy moth, in an overall yield of 60% in 5 steps. 相似文献
5.
将以烯烃为原料通过Sharpless不对称双羟化等多步反应合成的8种手性β-氨基醇, 作为有机小分子催化剂, 用于催化α,β-不饱和酮的不对称环氧化反应.考察了影响对映选择性的催化剂结构、催化剂用量、氧化剂种类、溶剂、反应温度等因素.结果表明, 当催化剂用量为30 mol%、氧化剂为TBHP(叔丁基过氧化氢)、正己烷溶剂、在室温下、以(1S,2R)-(+)-1,2-二苯基-2-甲氨基乙醇(3)作催化剂时, 所得环氧化物的对映体过量最高为70% ee, 产率最高为84%. 相似文献
6.
Kevin J. Quinn Kaylie E. GageCaroline M. Stanners Colin O. HayesKathleen E. Shanley Shalise M. Couvertier 《Tetrahedron letters》2014
Synthesis of the C2-symmetric, non-adjacent bis(tetrahydrofuran) core of cis-sylvaticin in seven steps and 24% overall yield from (2R,3S)-1,2-epoxy-4-penten-3-ol is reported. A strategy involving assembly of the central 1,4-diol unit by silicon-tethered ring-closing metathesis and subsequent two-directional functionalization, including establishment of the cis/threo stereochemical relationships of the tetrahydrofuran rings by Sharpless asymmetric dihydroxylation/SN2 cyclization, is employed. 相似文献
7.
Novel and Stereospecific Synthesis of (2S)‐3‐(2,4,5‐Trifluorophenyl)propane‐1,2‐diol from D‐Mannitol
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Derya Aktaş Meryem Fıstıkçı Özlem Gündoğdu Hasan Seçen M. Fethi Şahin Ramazan Altundaş Yunus Kara 《Helvetica chimica acta》2015,98(8):1127-1131
A stereospecific synthesis of (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol from D ‐mannitol has been developed. The reaction of 2,3‐O‐isopropylidene‐D ‐glyceraldehyde with 2,4,5‐trifluorophenylmagnesium bromide gave [(4R)‐2,2‐dimethyl‐1,3‐dioxolan‐4‐yl](2,4,5‐trifluorophenyl)methanol in 65% yield as a mixture of diastereoisomers (1 : 1). The Ph3P catalyzed reaction of the latter with C2Cl6 followed by reduction with Pd/C‐catalyzed hydrogenation gave (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol with >99% ee and 65% yield. 相似文献
8.
3-R-Boc-amino-4-(2,4,5-trifluorophenyl)butyric acid (9) was obtained from L-methionine in six steps with a total yield of 32%. The α-amino acid segment of L-methionine was transferred to chiral aziridine by amino protection, reduction, hydroxyl derivation, and cyclization. After ring opening of 2,4,5-trifluoro-phenyl magnesium bromide, the methylthiomethyl group was then hydrolyzed to β-amino alcohol and oxidized to the target β-amino acid. 相似文献
9.
《Tetrahedron: Asymmetry》1998,9(5):757-764
(2R,3R)-(+)- and (2S,3S)-(−)-2,3-epoxy-2-methylbutanoic acids (epoxyangelic acids) were prepared from (Z)-2-methyl-2-butenoic acid using the Sharpless asymmetric epoxidation method in combination with the use of (−)- and (+)-menthol as chiral auxiliaries. Both substances, obtained in high enantiomeric excess, were characterized by spectroscopic and optical activity data. Their absolute configuration was determined by correlation with (R)-(+)-2-methyl-1,2-butanediol. 相似文献
10.
Sharpless kinetic asymmetric epoxidation on (±)-2-(l-hydroxyethyl)-5,8-dimethoxy-3,4-dihydronaphthalene (8) followed by LAH reduction gave R-2-(S-l-hydroxyethyl)-2hydroxy-5,8-dimethoxy-1,2,3,4-tetrahydronaphthalene and the undesired antipode. The former was converted to R-(-)-2-acetyl-2 hydroxy-5,8-dimethoxy-l,2,3,4-tetrahydronapthalen[R-(-)-5],while the latter was epimerized and recycled. R-(-)-5 has been exploited for the synthesis of(+)-4-demethoxydaunomycin 相似文献
11.
研究了一种化学不对称合成盐酸(R)-沙丁胺醇的方法. 以自制的手性龙脑基β-二酮铁络合物为催化剂催化起始原料3-乙酰氧基甲基-4-乙酰氧基苯乙烯(1)的不对称环氧化, 得到(R)-3-乙酰氧基甲基-4-乙酰氧基苯基环氧乙烷(2), 这一步的化学收率和光学收率都较高. 然后环氧化合物2与叔丁胺发生开环反应, 再与盐酸成盐即制得盐酸(R)-沙丁胺醇. 合成盐酸(R)-沙丁胺醇只需两步, 总收率为68%. 还考察了反应温度、催化剂种类、催化剂的量等因素对3-乙酰氧基甲基-4-乙酰氧基苯乙烯(1)的不对称环氧化的化学产率和光学收率的影响. 相似文献
12.
O. V. Ardashov A. M. Genaev I. V. Il’ina D. V. Korchagina K. P. Volcho N. F. Salakhutdinov 《Russian Journal of Organic Chemistry》2010,46(12):1786-1789
Hydrogenation of (1R,2R,6S)-3-methyl-6-(1-methylethenyl)cyclohex-3-ene-1,2-diol was studied. Nickel chloride-sodium tetrahydridoborate system turned
out to selectively reduce the double bond in the isopropenyl group. The results of conformational analysis of (1R,2R,6S)-3-methyl-6-(1-methylethenyl)cyclohex-3-ene-1,2-diol and its partly and completely hydrogenated derivatives were in a good
agreement with the NMR data. 相似文献
13.
Stereoselective alkylation of the anion derived from (2R)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine with 2-chloromethylbenzothiophene afforded the corresponding trans-monosubstituted product, (2S,5R)-2-((1-benzo[b]thiophen-2-yl)methyl)-3,6-dimethoxy-5-(propan-2-yl)-2,5-dihyropyrazine in 88% yield. Hydrolysis of the alkylated product using 40% TFA/H2O at 0?°C and subsequent protection of the α-amino functional group with Fmoc-OSu afforded Fmoc-l-3-(2-benzothienyl)alanine methyl ester in 88% yield. Hydrolysis of the methyl ester with aqueous LiOH gave Fmoc-l-3-(2-benzothienyl)alanine in 62% overall yield. 相似文献
14.
A simple and effective procedure for the enantioselective synthesis of (R)- and (S)-moprolol was described. The key step was the asymmetric synthesis of enantiopure (R)- and (S)-guaifenesin, which were synthesized from enantioenriched (R)-3-chloro-l,2-propanediol and (S)-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-Co^Ⅲ complex. The e.e. values of both the optical compounds were above 98%, and the chemical structures of the target compounds were confirmed by ^1H NMR, ^13C NMR, IR, and MS. 相似文献
15.
An easy and efficient one-pot reaction from readily available 2-(N-Cbz) aminocyclobutanone selectively gave, by means of an asymmetric Strecker synthesis in the presence of a chiral benzylic amine, the thermodynamic 1,2-diamino nitriles. Basic hydrolysis, cleavage of the benzylic group and acidic hydrolysis of the resulting trans-1,2-diaminocyclobutanecarbonitrile gave, in a four-step sequence from the ketone, (1S,2S)- or (1R,2R)-1,2-diaminocyclobutanecarboxylic acid, ornithine derivatives. The absolute configuration has been established by X-ray analysis of the corresponding trans-diamino amide. 相似文献
16.
The Sharpless asymmetric epoxidation was used for the synthesis of D--dihydrosphingosine triacetate and (2, 3, 5)-2-acetamino-5,9-dimethyl-8-decene-1,3-diol, whose 13C-NMR study coupled with biogenetic consideration enabled us to propose (2, 3, 5,13, 14)-stereochemistry for aplidiasphingosine. 相似文献
17.
The synthesis of (S,S)-1,2-bis(3,5-di-tert-butylphenyl)ethane-1,2-diol (98.6% ee), which should be useful as a chiral ligand of catalysts in asymmetric inductions, is described. 相似文献
18.
Patrizia Scafato Stefania Labano Giovanni Cunsolo Carlo Rosini 《Tetrahedron: Asymmetry》2003,14(24):3873-3877
New diastereoisomeric phosphites based on either (R)- or (S)-2,2′-dihydroxy-1,1′-binaphthyl (BINOL) and having the chiral alcoholic moiety derived from the monobenzyl ether of (R,R)-1,2-diphenylethane-1,2-diol have been prepared and used as chiral ligands in the enantioselective copper-catalyzed 1,4-addition of diethylzinc to chalcone and 2-cyclohexen-1-one (enantiomeric excesses up to 48%). With the (aR,R,R) ligand dimethylzinc adds enantioselectively to (E)-cyclopentadecen-2-en-1-one to give (R)-(−)-muscone (68% yield, 78% ee). This provides an efficient access to a valuable ingredient of the perfume industry. However, with the (aS,R,R) ligand, (S)-(+)-muscone is obtained with longer reaction times (37% yield and 10% ee) with a very high double diastereoselection effect being observed. 相似文献
19.
In this study, (1R,2R)-1,2-bis-(5-amino-1,3,4-thiadiazol-2-yl)ethane-1,2-diol (2), was synthesized by using (2R,3R)-(+)-Tartaric acid (1) as starting compound. Then the diazo component 3 was obtained from 2 and 1-naphthol. In addition, the structures of the synthesized compounds 2 and 3 were confirmed by elemental analyses, IR, 1H-NMR, and 13C-NMR spectra.
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Published in Kimiya Prirodnikh Soedinenii, No. 5, pp. 465–466, September–October, 2005. 相似文献
20.
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