共查询到20条相似文献,搜索用时 10 毫秒
1.
Both the enantiomers of trans-3-hydroxypipecolic acid have been synthesized employing the Sharpless asymmetric dihydroxylation and epoxidation as the key steps starting from a commercially available starting material 1,4-butanediol. 相似文献
2.
Shibata N Nishimine T Shibata N Tokunaga E Kawada K Kagawa T Sorochinsky AE Soloshonok VA 《Chemical communications (Cambridge, England)》2012,48(34):4124-4126
Organic base-catalyzed reaction of (S)-N-tert-butanesulfinyl (3,3,3)-trifluoroacetaldimine with dialkyl malonates was found to be effective for synthesis of both (S,S(S)) and (R,S(S)) β-aminomalonates in high yield with good to excellent diastereoselectivity (76-98% de). The products of this Mannich reaction provide direct access to β-trifluoromethyl-β-alanine of either (R) or (S) absolute configuration. 相似文献
3.
Annamaria Varga Valentin Zaharia Mihály Nógrádi László Poppe 《Tetrahedron: Asymmetry》2013,24(21-22):1389-1394
Ethyl (S)-3-hydroxy-3-phenylpropionate (S)-2 was obtained by the asymmetric reduction of ethyl 3-phenyl-3-oxopropionate 1 with the yeast Saccharomyces cerevisiae (ATCC 9080). The kinetic resolution of racemic ethyl 2-acetoxy-3-phenyl-propionate rac-3 with the same microorganism, gave after hydrolysis ethyl (R)- and (S)-3-hydroxy-3-phenylpropionates (R)-2 and (S)-2 which were converted by a straightforward series of reactions to the enantiomers of 3-amino-3-phenyl-propionic acids (S)-6 and (R)-6. The asymmetric reduction and hydrolytic kinetic resolution were also tested with several other whole cell systems under a variety of conditions. 相似文献
4.
《Tetrahedron: Asymmetry》1999,10(11):2213-2224
An acetal protected 4-amino-2-pentanone was synthesised by two different routes in 10 and seven steps, respectively, the key step being a microbiological reduction. Both enantiomers of the amine were obtained enantiomerically pure. 相似文献
5.
Abbiati G Clerici F Gelmi ML Gambini A Pilati T 《The Journal of organic chemistry》2001,66(19):6299-6304
The enantioselective synthesis of 2-amino-3-hydroxynorbornene-2-carboxylic acid derivatives (5) was studied using the Diels-Alder reaction between cyclopentadiene and different dienophiles, i.e., alkyl 5-oxo-2-phenyloxazol-4-methylenecarbonates (1) or 2-benzoylamino-3-alkoxycarbonyloxy-acrylates (12), operating with different Lewis acids and both with thermal and with ultrasound conditions. The enantioselective synthesis of the exo/endo compounds 5c,d and 5'c,d was achieved starting from the chiral menthyl acrylates 12b,c using Mg(ClO(4))(2) as the catalyst and ultrasound. The cycloadducts were obtained in very good yield, in mild conditions, in short time, and in good diastereomeric excess (exo, 80%; endo, 87%). Finally, the use of alkylidene-oxazolones or acrylates and EtAlCl(2) or Mg(ClO(4))(2) as the catalyst allowed control of the cycloaddition reaction in favor of the exo or endo products. 相似文献
6.
《Tetrahedron: Asymmetry》2000,11(10):2211-2219
An improved enantioselective synthesis (five steps, 37–44% yield versus seven to 10 steps, 13.5 and 12% yield, respectively) of both enantiomers of keto-protected 4-amino-2-pentanone has been realized, the key step being the microbiological reduction of 2,4-pentanedione. This study shows that microbiological reductions of the mono acetal-protected 2,4-pentanedione afforded in most cases the corresponding ketol with moderate to excellent enantiomeric excesses, depending on the microorganism used. 相似文献
7.
8.
Chun-min Zeng John A. Katzenellenbogen Kyla Gallacher C. Richard Lyttle Chris P. Miller 《Tetrahedron letters》2010,51(41):5361-5363
An efficient synthesis of the non-proteinogenic amino acid (2R,3S)-4,4,4-trifluoro(OBn)-threonine is described. Starting with commercially available (S)-Garner’s aldehyde, the desired amino acid was prepared as its hydrochloride salt in five steps and an overall yield of 33% (59% based on recovered starting material). The utility of this unusual amino acid was demonstrated by its elaboration into a potent and selective androgen. 相似文献
9.
Chemoenzymatic asymmetric synthesis of antidepressant agent venlafaxine and its analogue have been reported in this communication. The main highlight of the reported synthesis is the stereoselective synthesis of cyanohydrins by (S)-hydroxynitrile lyase (Hevea brasiliensis) followed by lipase catalyzed kinetic resolution. 相似文献
10.
Asymmetric synthesis of (+)-phosphinothricin, (+)-2-amino-4-phosphono-butyric acid, and their enantiomers has been achieved by the Michael addition of chiral glycine Schiff bases to vinyl phosphorus compounds. 相似文献
11.
《Tetrahedron: Asymmetry》1999,10(12):2327-2336
Asymmetric synthesis of 3-amino-2-hydroxy-4-phenylbutanoate, a key component of the natural product bestatin and HIV protease inhibitors of KNI-272 and R-87366, has been achieved from the stereoselective aldimine coupling reaction between 3-phenyl-2-aminopropanenitrile and (Z)-α-methoxy trimethylsilyl ketene acetal in the presence of Lewis acids. 相似文献
12.
《Tetrahedron: Asymmetry》2006,17(13):1979-1984
Both antipodes of α-methyl-α-methoxyarylacetic acid derivatives were prepared from a common chiralpool precursor l-(+)-tartaric acid. The key step involves the addition of Grignard reagents to 1,4-diketones derived from tartaric acid. The utility of this strategy was applied in the formal enantioselective synthesis of pine beetle pheromone (−)-frontalin. 相似文献
13.
The first application of metalloenamines derived from N-sulfinyl imines is reported for the highly diastereoselective addition to aldehydes. Reduction of the beta-hydroxy-N-sulfinyl imine products with catecholborane and LiBHEt3 provides syn- and anti-1,3-amino alcohol derivatives, respectively, with very high diastereomeric ratios. 相似文献
14.
The use of several chiral trifluoromethylated building blocks 1a, 1b, 9a and 9b was attempted to synthesize of syn-(3-trifluoromethyl)cysteine. A novel and efficient enantioselective synthesis of both enantiomers of syn-(3-trifluoromethyl)cysteine derivatives 12a and 12b was successfully achieved. 相似文献
15.
16.
《Tetrahedron: Asymmetry》1999,10(17):3403-3407
A facile synthesis of both enantiomers of trans-cyclohex-4-ene-1,2-dicarboxylic acid on a multigram scale, that starts from inexpensive, commercially available compounds, is described. 相似文献
17.
Based on the lipase-catalysed kinetic resolution of the silyloxyalcohol (1RS,2SR)-5 by transesterification with vinyl acetate in the presence of lipase from Pseudomonas cepacia a synthesis of both enantiomers of the β-amino acid cispentacin (1R,2S)-1 and (1S,2R)-1 using simple functional group interconversions is described. 相似文献
18.
Gowrisankar Reddipalli Mallam Venkataiah Nitin W. Fadnavis 《Tetrahedron: Asymmetry》2010,21(3):320-324
The synthesis of both the (R)- and (S)-enantiomers of the natural product rugulactone has been achieved. Candida rugosa lipase hydrolyzes the butyrate ester of the protected 3-hydroxy homoallylic alcohol with very high enantioselectivity (E = 244) and provides the key intermediates with high enantiomeric purity (ee 98–99%) and excellent yields. 相似文献
19.
The stereoselective total synthesis of both enantiomers of rugulactone 1 has been completed by applying enantioselective allyl additions as key steps. Two different strategies based on highly stable and enantiomerically pure α-substituted allylboronic esters 2 and 3 were performed starting from boronic ester 4. 相似文献