Racemic Allylic Alcohols Research Articles

リパーゼが触媒する不斉合成反応の新展開

The lipase-catalyzed transesterification of alcohols with acyl donors in organic media has gained increased attention as a powerful method for the preparation of optically enriched compounds under very mild conditions, in which the vinyl esters 2 have been most frequently employed as the acyl donors; however, they are not always satisfactory.We applied the ethoxyvinyl esters 6 to the lipase-catalyzed transesterification reactions for the first time and discovered their advantages, viz., (i) the efficient reactivity and enantiotopic selectivity similar to or higher than those of 2 and (ii) the ready availability of the esters 6 having a suitably functionalized acyl moiety from the corresponding carboxylic acids and their applicability to the enzymatic reactions. These findings have opened a new possibility of the lipase-catalyzed reactions. In this review, several examples are introduced along with some related recent progress on the lipase-catalyzed asymmetric syntheses. The topics include (i) the enantioselective desymmetrization of prochiral 2, 2-disubstituted 1, 3-propanediols using 1-ethoxyvinyl 2-furoate 6b, (ii) the lipase-catalyzed domino reactions using suitably functionalized acyl donors 6e-i for the direct preparation of optically enriched cyclic compounds having multi stereogenic carbon centers, (iii) the dynamic kinetic resolution (DKR) of racemic secondary alcohols by the combined use of lipases and the ruthenium complexes 36a-g, and (iv) the DKR of racemic allylic alcohols (44, 45) by the combination of lipases and the vanadium compound 43. Application of these reactions to the asymmetric total synthesis of natural products is also described.

Kinetic Resolution of Allylic Alcohols Promoted by Electrophilic Selenium Reagents.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Chiral Electrophilic Selenium Reagent to Promote the Kinetic Resolution of Racemic Allylic Alcohols.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Kinetic Resolution of Allylic Alcohols Promoted by Electrophilic Selenium Reagents

The first example of a kinetic resolution process promoted by an electrophilic selenium reagent is reported. Racemic allylic alcohols react with half equivalents of a selenenylating agent in methanol leading to the regiospecific formation of the corresponding addition products with a very high level of facial selectivity (98% de). The unreacted alcohol can be recovered in a optically enriched form (92% ee).

A Chiral Electrophilic Selenium Reagent To Promote the Kinetic Resolution of Racemic Allylic Alcohols

[reaction: see text] The first example of a kinetic resolution process promoted by electrophilic selenium reagents is reported. Racemic allylic alcohols react with half equivalents of a selenenylating agent in methanol leading to the regiospecific formation of the corresponding addition products with a very high level of facial selectivity (from 95:5 to 98:2 dr). The unreacted alcohols can be recovered in an optically enriched form (from 90 to 94% ee).

Enantioselective synthesis of a mitosane core assisted by diversity-based catalyst discovery.

[reaction: see text]. Synthesis of mitosane 1 in optically pure form is reported. A retrosynthetic plan that proceeds through racemic allylic alcohol 3 was carried out. This intermediate served as a test substrate for a rapid screen of a small library (152 members) of peptide-based kinetic resolution catalysts. Peptide 9 was found to effect kinetic resolution with k(rel) = 27. Alcohol (-)-3 was then converted to optically pure (-)-1 in eight steps.

Kinetic resolution of allylic alcohols using a chiral phosphine catalyst.

[reaction: see text] The kinetic resolution of racemic allylic alcohols 3, 6, and 12--17 has been explored using the PBO catalyst 7 for activation of isobutyric anhydride. Trisubstituted allylic alcohols (12--15; 17) are the best substrates and react with an enantioselectivity of s = 32--82 at -40 degrees C.

Enzyme-Mediated Preparation of (+)- and (-)-cis-α-Irone and (+)- and (-)-trans-α-Irone

The preparation of (−)- and (+)-trans-α-irone (1a and 1b, resp.) and of (+)- and (−)-cis-α-irone (1c and 1d, resp.) from commercially available Irone alpha ® is reported. The relevant step in the synthetic sequence is the initial chromatographic separation of crystalline (±)-4,5-epoxy-4,5-dihydro-cis-α-irone ((±)-5) from oily (±)-4,5-epoxy-4,5-dihydro-trans-α-irone ((±)-4). The latter was subsequently converted, after NaBH4 reduction, into the crystalline 3,5-dinitrobenzoate ester (±)-8, thus allowing a complete separation of the two corresponding diastereoisomeric alcohol derivatives. Suitable enantiomerically pure precursors of the desired products 1a – d were obtained by kinetic resolution of the racemic allylic alcohols derived from (±)-5 and (±)-8, mediated by lipase PS (Amano). The last steps consisted of MnO2 oxidation and removal of the epoxy moiety with Me3SiCl/NaI in MeCN. External panel olfactory evaluation showed that (−)-cis-α-irone (1d) has the finest and most distinct `orris butter' character.

Efficient stereoselective synthesis of the epoxyacid fragment of the azinomycins

Three concise enantioselective synthetic routes to the C17C21 epoxyacid segment of the azinomycins are presented and were based on a Sharpless asymmetric epoxidation/kinetic resolution of racemic allylic alcohol (±)- 3 that occurred with reversal of the expected sense of enantioselection.

Resolution of Allylic Alcohols via Copper(I) Complexes with a Chiral Diamine

By using the Corey diamine 1,2-diphenyl-N,N′-bis[(2,4,6-trimethylphenyl)methyl]-1,2-diaminoethane, Copper(I) olefin complexes are prepared. When the olefin is a racemic allylic alcohol, selective coordination of one enantiomer is observed. Cleavage with aqueous HCl or NaCN allows a two-steps resolution affording excellent enantiomeric excess.

A new, versatile and stereospecific route to unusual amino acids: the enantiospecific total synthesis of statine amide and its three stereoisomers

Total syntheses of statine amide [(3S,4S)-4-amino-3-hydroxy-6-methylheptanamide] and its three stereoisomers are described in order to illustrate the versatility of a new route to β-hydroxy-γ-amino acids. The enantioselective Sharpless epoxidation of a racemic allylic alcohol is used to generate chiral intermediates. The allylic alcohol, 3-hydroxy-5-methyl-1-hexene, can be prepared in at least two different ways from readly available materials. The methodology that is described should prove applicable to the synthesis of other analogues of statine

Chemical Resolution of Allylic Alcohols

Abstract Asymmetric epoxydation of a racemic allylic alcohol followed by acetylation, chromatography, and deoxygenation (WCl6, n-BuLi) has led to the individual optically active enantiomers.

ChemInform Abstract: Stereospecific Telluride‐Mediated Conversion of Glycidols to Allyl Alcohols: An Extension of the Sharpless Kinetic Resolution.

AbstractThe racemic allylic alcohols (±)‐(I) are kinetically resolved by Sharpless epoxidation to give the chiral oxiranes (II) and the chiral alcohols (+)‐(I).

ChemInform Abstract: A Practical Synthesis of Several Polyhydroxylated Chiral Building Blocks.

AbstractSharpless epoxidation of the racemic allylic alcohols (±)‐(I) yields selectively the epoxides (II).

Kinetic resolution of racemic allylic alcohols by BINAP-ruthenium(II) catalyzed hydrogenation

Dedoublement optique d'alcools allyliques aliphatiques ou monocycliques comme le cyclohexene-2ol ou le methyl-2 nonene-2 ol-4

ChemInform Abstract: DEVELOPMENT OF A NOVEL SYNTHETIC ROUTE TO OPTICALLY ACTIVE ANTHRACYCLINONES: PRELIMINARY SYNTHESIS OF THE RACEMIC KEY INTERMEDIATE

AbstractIn der ersten Arbeit wird ein Verfahren beschrieben, um aus der Dihydronaphthalincarbonsäure (I) über das Keton (III), den Alkohol (IV) und das Diol (Va) das Hydroxyketon (VI) herzustellen, das mit Phthalsäureanhydrid (VII) in die Anthracyclinone (VIII) übergeführt wird.

Development of a novel synthetic route to optically active anthracyclinones: Preliminary synthesis of the racemic key intermediate.

In order to develop a novel synthetic route to a key synthetic intermediate ((R)-(-)-3) for optically active anthracyclinones (2a-d), preparation of the racemic intermediate ((±)-3) from the α, β-unsaturated ketone (6), obtainable from the α, β-unsaturated acid (5) or the 2-tetralone (11), was attempted according to the designed synthetic scheme. Since epoxidation of the racemic allylic alcohol ((±)-7) produced by reduction of 6, followed by reductive cleavage of the epoxides ((±)-8a, b) and oxidation of the vicinal-diol ((±)-9a), was found to readily give the desired (±)-3 in good overall yield, optically pure (R)-(-)-3 should be obtainable from 6 if 6 can be asymmetrically reduced to afford (S)-7 in a high optical yield. The racemic ketone ((±)-3) was further transformed to (±)-7-deoxy-4-demethoxy-daunomycinone dimethyl ether ((±)-13), from which racemic 4-demethoxyanthracyclinone ((±)-2c, d) could be elaborated.

Kinetic resolution of racemic allylic alcohols by enantioselective epoxidation. A route to substances of absolute enantiomeric purity?

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic resolution of racemic allylic alcohols by enantioselective epoxidation. A route to substances of absolute enantiomeric purity?Victor S. Martin, Scott S. Woodard, Tsutomu Katsuki, Yasuhiro Yamada, Masonari Ikeda, and K. Barry SharplessCite this: J. Am. Chem. Soc. 1981, 103, 20, 6237–6240Publication Date (Print):October 1, 1981Publication History Published online1 May 2002Published inissue 1 October 1981https://doi.org/10.1021/ja00410a053RIGHTS & PERMISSIONSArticle Views6412Altmetric-Citations694LEARN 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 (573 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts