Chiral C2 Research Articles

ChemInform Abstract: Preparation and Enantiomeric Purity Determination of New Chiral C2 Building Blocks Based on the 4‐Amino‐1,2,4‐triazole Unit.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Enantioselective Ethylation of Aldehydes Catalyzed by Chiral C2‐ Symmetrical β‐Hydroxy‐m‐xylylene Diamines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

C 2 Diamine, pseudo-C 2 poly(amide) and poly(urea) as chiral inductors in asymmetric catalysis

Chiral C2 diamine, poly(amide) and poly(urea) act as inductors both in asymmetric hydride transfer reduction of acetophenone and carbon–carbon bond formation with high enantioselectivity of up to 95% enantiomeric excess.

ChemInform Abstract: Production of Chiral C3 Units Based on Microbial Resolution and Their Synthetic Applications

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and Crystal Structure of Benzyl (—)-(2S)-1-trityl-2-aziridinecarboxylate

Benzyl (–)-(2S)-1-trityl-2-aziridinecarboxylate (1) has been prepared by the reaction of N-trityl-L-serine benzyl ester and triethylamine in toluene with SO2Cl2. X-ray, 1H NMR and gas chromatographic configuration analysis allowed to define the structure of the compound as a trans-isomer regarding ring substituents and as a (2 S)-enantiomer of the chiral C2.

Asymmetric selenomethoxylation of olefins involving a chiral C2 symmetrical electrophilic organoselenium reagent

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAsymmetric selenomethoxylation of olefins involving a chiral C2 symmetrical electrophilic organoselenium reagentRobert Deziel, Sylvie Goulet, Louis Grenier, Josee Bordeleau, and Julie BernierCite this: J. Org. Chem. 1993, 58, 14, 3619–3621Publication Date (Print):July 1, 1993Publication History Published online1 May 2002Published inissue 1 July 1993https://doi.org/10.1021/jo00066a010RIGHTS & PERMISSIONSArticle Views387Altmetric-Citations70LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (331 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Reactions of Chiral Phosphorous Acid Diamides

Abstract Chiral phosphorous acid diamides were prepared from chiral C2 diamines via the sequential addition of PCl3 and H2O. Alternatively, addition of PCI3 and hydrogen sulfide yieded the analogous thiophosphorous acid diamides. Deprotonation of the phosphorous acids under a variety of conditions gave the anions which reacted smoothly with alkyl halides to give phosphonamides in good yield. Reaction of the anions with aldehydes gave α-hydroxy-phosphonamides in good yield and with modest diastereoselectivity (1:1 - 25:1 ds). Treatment of the phosphorous acids with trialkylsilyl triflates and Hunnig's base gave the product of O-silylation.

微生物を利用した光学活性なＣ３合成ユニットの開発とその応用

We developed to produce optically pure glycerol derivatives, such as (R) and (S)-2, 3- dichloro-1-prop-anols, and (R) and (S)-3-chloro-1, 2-propanediols, based on microbial resolution. These compounds are precursors of optically active epichlorohydrins and glycidols which are used for wide variety of organic syntheses. We describe here the new methods to obtain these chiral C3 units and their several synthetic applications.

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Autoassembly of cage structures. 4. Stereochemistry of 2,5-di-tert-butyl-?-butyrolactone-4-carboxy-s-(?)-phenylethylamide

The diastereoisomeric lactonamides (2a, b), obtained from the dilactone (1) and S-phenylethylamine, have been separated. X-ray crystallography shows that the high-melting isomer (2a) has theR-configuration at the chiral centers C2 and C4, the enantiomeric conformation of the γ-lactone ring being of theS-type in thetwist form, intermediate between envelope 2 E and semi-chair 3 2 T. It is shown by molecular mechanics that the minimum steric energy of2a corresponds to a conformation of the heterocycle close to the envelope form3E. Examination of van der Waals interactions shows that the calculated structure for2a is preferred. The reasons for the nonidentity of the forms of the γ-lactone ring of2a in the crystal and the free state are discussed. The crystal structure of2a is composed of two geometrically similar independent molecules associated along the axis by weak hydrogen bonds of two types, the energies of which have been estimated from the vXH values, which are related by the expression vXH=f(RX...O), where X=N, O.

ChemInform Abstract: Glycidyl Derivatives as Chiral C3 Synthons. Ring Opening Catalyzed by BF3 Etherate.

AbstractThe high regio‐ and stereoselectivity of the title reaction allows the preparation of optically active, monoprotected vic‐diols such as (III) and (VI), some of which are known as useful building blocks in carbohydrate, terpene and alkaloid chemistry (e.g.

Total Synthesis of Erythronolide A

Abstract The enantiospecific total synthesis of erythronolide A (1) through (9S)-9-deoxo-9-hydroxyerythronolide A (2) from the chiral C1–C6, C7–C9, and C10–C13 synthetic segments is described. The C10–C13 segment, (3R,4R,5R)-5-O-benzyl-2-iodo-3,4-O-isopropylidene-4-methyl-1-heptene-3,4,5-triol (11) was synthesized in 16 steps and an 8.3% overall yield from d-ribose. The C7–C9 segment, (S)-(+)-2-(2-bromo-1-methylethyl)-1,3-dioxolane (47) was prepared from methyl (S)-(+)-3-hydroxy-2-methylpropionate in 8 steps and a 49% overall yield. The coupling of the Grignard reagent, prepared from magnesium and 47, and the C1–C6 segment, 3,5,7-tri-O-benzyl-1,4,6-trideoxy-4,6-di-C-methyl-keto-l-ido-2-heptulose (13), afforded 5,7,9-tri-O-benzyl-2,3,6,8-tetradeoxy-2,4,6,8-tetra-C-methyl-l-threo-l-ido-nonose ethylene acetal (48) and its C4-epimer in 79% and 8% yields, respectively. 5,7,9-Tri-O-benzyl-4-O-t-butyldimethylsilyl-2,3,6,8-tetradeoxy-2,4,6,8-tetra-C-methyl-l-threo-l-ido-nonose (12), derived from 48, was subjected to coupling reaction with the lithium reagent prepared from 11 to afford about 5:1 excess of the “Cram” product 50. The homogeneous hydrogenation of 50 with [ClRh(Ph3P)3] gave 1,3,5,13-tetra-O-benzyl-6-O-t-butyldimethylsilyl-2,4,7,8,10,14,15-heptadeoxy-11,12-O-isopropylidene-2,4,6,8,10,12-hexa-C-methyl-d-arabino-d-gluco-l-ido-pentadecitol (54) and its C10-epimer in 41% and 7% yields from 12, respectively. The conversion of 54 to 2 was accomplished by a sequence of reactions including the Corey–Nicolaou lactonization method in a 17% overall yield. Selective 3,5-O-benzylidenation of 2 followed by PCC oxidation and debenzylidenation gave 1 in 52% yield.

Glycidyl derivatives as chiral C3 synthons. Ring opening catalyzed by boron trifluoride etherate

Glycidyl derivatives as chiral C3 synthons. Ring opening catalyzed by boron trifluoride etherate

Pterins. VIII. The absolute configuration at C 6 of natural 2-Amino-6-[(1'R,2'S)- 1',2'-dihydroxypropyl]-5,6,7,8-tetrahydropteridin-4(3H)-one (L-erythro-5,6,7,8-tetrahydrobiopterin)

The conformation of the side chain of 5,6,7,8-tetrahydrobiopterint (6) in 0.5 M DCl/D2O is predominantly quasi-equatorial (deduced from 3J (13C4a, 1H6) 1.1 HZ), and is the same as that of the methyl group in 2-methyl-1,2,3,4-tetrahydroquinoxaline and in 2-amino-6-methyl-5,6,7,8-tetrahydropteridin-4(3H)-one in the same solvent. Because (-)-(2S)-2-methyl-1,2,3,4-tetrahydroquinoxaline(4) and (-)-(6S)-2-amino-6-methyl-5,6,7,8-tetrahydropteridin-4(3H)-one (5) have the same conformation and negative c.d. spectra (O 248 nm and 263 nm respectively) as does the natural 5,6,7,8, tetrahydrobiopterin (O minimum at 265 nm) in 0.1 M hydrochloric acid, then the absolute conformations of the tetrahydropyrazine rings and the absolute configurations at the chiral centres C2, C6, and C6 of compounds (4), (5) and (6) respectively are the same. Hence the absolute configuration at C6 in natural 5,6,7,8 tetrahydrobiopterin is R.� A convenient synthesis of biopterin on a gram scale is described.

Synthese von vier chiralen, elektrophilen C3‐ und C4‐Synthesebausteinen aus Hydroxycarbonsäuren

Synthesis of four chiral electrophilic C3‐ and C4‐synthons from hydroxycarboxylic acidsThe chiral alkylating reagents 4, 6c, and 10a/b are prepared from lactic, β‐hydroxy butyric, and malic acid, respectively. Their use in natural product synthesis is referred too.