共查询到20条相似文献,搜索用时 15 毫秒
1.
N. G. Morozova Yu. G. Sachkova G. A. Serebrennikova L. V. Volkova R. P. Evstigneeva 《Chemistry of Natural Compounds》1991,27(1):12-14
The stereoselective synthesis of a -D-phosphatidylgalactose has been achieved by the interaction of a benzyl phosphatidate with D-galactose tert-butyl orthoacetate or trichloroacetimidate.M. V. Lomonosov Institute of Fine Chemical Technology, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 16–19, January–February, 1991. 相似文献
2.
A straightforward, highly stereoselective protocol toward the synthesis of deuterium-labeled (2R,3S,4S)-β-cyclohexenylserine has been developed. Key steps are a Nozaki-Hiyama-Kishi reaction generating the stereogenic centers and a ring-closing metathesis for the construction of the cyclohexenyl ring system. The labeled amino acid was further activated as an SNAc-ester for feeding experiments. 相似文献
3.
Joshua Chola 《Tetrahedron letters》2008,49(39):5680-5682
Stereoselective syntheses of racemic (1S,2R,3R,4R,5S,6R)- and (1S,2R,3R,4S,5S,6R)-3,4,5,6-tetrahydroxy derivatives of 2-aminocyclohexanecarboxylic acid have been achieved by a stereospecific Diels-Alder reaction between furan and maleic anhydride, a Curtius rearrangement and hydroxylation reactions. 相似文献
4.
Shu-Wei Yang Xin Linghu Elizabeth Smith Jianping Pan Victoria Sprague Jing Su 《Tetrahedron letters》2017,58(29):2838-2841
We have developed highly efficient chemistry to prepare two key intermediates from a Relabactam intermediate available from the process chemistry. The new intermediates enabled us to quickly synthesize other Ralebactam derivatives such as compound 1. 相似文献
5.
The first report on the use of N-sulfinyl benzylcarbamate for the preparation of N-Cbz sulfilimine from the corresponding sulfoxide is reported. The sulfilimine moiety is utilized as an intramolecular nucleophile for the regio- and stereoselective heterofunctionalization of an alkene to furnish a bromo carbamate which is used as a key advanced intermediate in the synthesis of representative α-hydroxy-β-amino acid derivatives. 相似文献
6.
Aitken DJ Drouin L Goretta S Guillot R Ollivier J Spiga M 《Organic & biomolecular chemistry》2011,9(21):7517-7524
The Kulinkovich-de Meijere reaction between an unsaturated Grignard reagent and a chiral amide takes place with a high trans stereoselectivity and provides a convenient access to non-racemic trans cyclopropylamines. These compounds are transformed in four steps into the corresponding N-protected β,γ-methano-GABA derivatives, which are obtained for the first time in enantiomerically pure form. The corresponding transformations of the cis cyclopropylamine adducts are also described. 相似文献
7.
《Tetrahedron: Asymmetry》1999,10(23):4553-4561
α-Alkylation of N-tosyl-protected β-amino esters with LDA as the base led to high anti selectivity for the newly formed C–C bond. The α-alkylated β-amino esters were further transformed to enantiomerically pure 4,5-disubstituted pyrrolidinones through hydrolysis, diazotization, and Wolf rearrangement under AgO2CPh/Et3N/dry THF conditions. 相似文献
8.
《Tetrahedron: Asymmetry》1999,10(14):2655-2663
Here we describe a one-pot synthesis of a series of β-substituted amines as single enantiomers from an initial regioisomeric mixture of styrene oxide ring-opening products. We also report the isolation and characterization of a key β-chloro intermediate and provide additional insight into the mechanism of the reported alkylations. These results require that the reaction proceeds through a common aziridinium ion intermediate on two separate occasions in order to account for the observed overall net retention of configuration in proceeding from (S)-styrene oxide to the desired β-substituted amine products. 相似文献
9.
《Tetrahedron: Asymmetry》2000,11(13):2741-2751
The four stereoisomers of Δ2-isoxazoline 2, a β-adrenergic receptor antagonist structurally related to Falintolol 1, were prepared by an enzyme-catalyzed kinetic resolution of the unsaturated secondary alcohol (±)-7 followed by its cycloaddition to pyruvonitrile oxide. Through this strategy, diastereomeric aminoalcohols (+)-2a/(−)-2b and (−)-2a/(+)-2b were obtained in 99 and 92% enantiomeric excess, respectively. The absolute configuration to the target compounds was assigned via chemical correlation to the enantiomers of epoxides 4a and 4b, whose stereochemistry had been previously established. 相似文献
10.
Subbiah Nagarajan Pandian Arjun Nanjian Raaman Anup Shah M. Elizabeth Sobhia Thangamuthu Mohan Das 《Tetrahedron》2012,68(14):3037-3045
Highly diastereoselective synthesis of cis-β-lactams via [2+2] cycloaddition reactions of sugar-imine derivative possessing free hydroxyl groups at C-2 and C-3 positions and ketenes is described. exo-Approach of sugar-imine with ketene leads to the stereoselective formation of cis product and it is facilitated by hydrogen bonding interaction of C2–OH with carbonyl group of ketene. Docking studies show that these derivatives are having greater affinity towards PBP and it has been validated by in vivo studies. Among the different sugar-based azetidine-2-ones, compounds 6a and 6d were superior in activity to the commercial antibiotic tetracycline. 相似文献
11.
《Tetrahedron: Asymmetry》1999,10(12):2361-2371
trans-N-Benzyl-3-trifluoromethyl-2-ethoxycarbonylaziridine 2a, easily obtainable in enantiopure forms by CAL-catalysed enzymatic resolution, allowed the regio- and stereoselective synthesis of chiral fluorinated anti-α-functionalised-β-aminoacids, such as trifluoroisoserinates or trifluoro-β-alanine, and trans-3-halo- or 3-hydroxy-β-lactams. Starting from the enantiomerically pure methyl analogue of the title compound, 2c, pure enantiomers of trifluoroisoserine can be obtained in high overall chemical yield. Absolute configurations of optically active β-aminoacids were determined by chemical correlation. 相似文献
12.
Stereoselective synthesis of benzyl-protected β-galactosides by propionitrile-mediated glycosylation
Akiharu Ueki Masafumi Hirota Keiko Komatsu Yutaka Takano Michio Iwaoka Hironobu Hojo Yoshiaki Nakahara 《Tetrahedron》2008,64(11):2611-2618
β-Selective galactosylation was studied using a series of 2-O-benzylated phenyl 1-thio-galactosides and glycosyl acceptors in propionitrile with BSP-TTBP-Tf2O. The glycosylation enabled us to synthesize useful precursors of N-acetyllactosamine and core 1 O-glycoserine derivatives in a highly convergent manner. 相似文献
13.
The β-glycosyl esters of cis-cinnamic acid were synthesized directly using Hannesian’s unprotected glycosyl donor and the carboxylic acid in toluene. This protocol does not require protecting groups on the glycosyl donors, and high stereoselectivity was achieved. The first synthesis of a potent allelochemical, 1-O-cis-cinnamoyl-β-d-glucopyranose, is also described. 相似文献
14.
V. I. Boev A. I. Moskalenko S. L. Belopukhov G. N. Nikonova 《Russian Journal of Organic Chemistry》2016,52(5):628-635
Decarboxylation of α-allyl-substituted acetoacetic esters afforded α-allyl ketones that were reduced with L-selectride [LiBH(s-Bu)3] in alcohols RCH(OH)CH2CH2CH=C(Me)CH2R'. The latter reacted with methyl 4-hydroxy-3-formylbenzoate and methyl orthoformate in the presence of p-toluenesulfonic acid to provide trans-tetrahydropyrano[3,2-с][1]benzopyran. In reaction of the E-isomer of alcohol Me2CHCH(OH) CH2CH2CH=C(Me)CH2CH2Ph with CF3SO3H a stereoselective cyclization occurred with the formation of 2,6-disubstituted tetrahydropyran; Prins reaction with 4-bromobenzaldehyde and salicylaldehyde in the presence of boron trifluoride etherate also proceeded stereoselectively giving a substituted tetrahydropyrano-[3,2-c][1]-benzopyran. 相似文献
15.
16.
A stereoselective methodology was developed for the construction of C-spiro-glycosides in two steps involving bromonium ion activated solvolytic ring opening of sugar derived 1,2-cyclopropanecarboxylates followed by a one-pot dehydrohalogenation, intramolecular hetero-Michael addition (IHMA) and ester hydrolysis. The obtained spirocyclic lactols were further converted to enantiomerically pure spirolactones. 相似文献
17.
《Tetrahedron: Asymmetry》2001,12(14):2009-2011
A novel stereoselective synthesis of (−)-cytoxazone 1 was achieved via addition of p-methoxyphenylmagnesium bromide to the benzylimine derived from (S)-2,3-O-isopropylidene glyceraldehyde followed by one-step regioselective cyclization of N-Boc amino diol 7. 相似文献
18.
《Tetrahedron: Asymmetry》1998,9(10):1703-1712
The additions of organolithium reagents to the CN bond of several chiral oxime ethers derived from erythrulose afforded protected amino polyols with high diastereoselectivity. Four of the latter compounds have been converted into the α,α-disubstituted α-amino acids (R)-2-(−)-methylserine, (S)-2-(+)-methylserine, (R)-(+)-2-phenylserine and (R)-(−)-2-n-butylserine. 相似文献
19.
《Tetrahedron: Asymmetry》2003,14(15):2229-2238
Ring opening of oxazolines, prepared from l-serinates, with trimethylsilyl halides (TMSX) led to β-halogeno-N-benzoyl-α-amino esters in good to excellent yields. Quaternization of triphenylphosphine by the β-bromo or -iodo amino esters gave the corresponding β-phosphonium salts in overall yields of up to 93% and with e.e. >96%. Hydrolysis of the ester function afforded the phosphonium salt bearing an N-benzoyl-α-amino acid substituent, with partial racemization. However, the reaction of the TMSX with the carboxylic salt, prepared by saponification of the starting oxazoline ester, furnished the corresponding β-halogeno-N-benzoyl-α-amino acids in 70–95% yields. Quaternization of triphenylphosphine by the bromo or iodo derivatives led to the phosphonium salts bearing a free acid function in 95% yield, without racemization. The efficiency of this synthesis was demonstrated by the preparation of these phosphonium salts in excellent overall yields, by a one-pot procedure starting from the oxazoline. 相似文献
20.
《Tetrahedron letters》1986,27(48):5811-5812
Isomeric enol ester, enamine, and silyl enol ether derivatives of unsymmetrical ketones are converted regiospecifically to α-arylsulfonoxy ketones with arylsulfonyl peroxides. 相似文献