Β-hydroxy Ketones Research Articles

Construction of functionalised medium rings by stereospecific expansions of 2,3-epoxy alcohols under mild conditions

Ketones are converted with very high stereocontrol into functionalised medium rings incorporating a β-hydroxy ketone assembly via a ring-expansion mediated by tin(IV) chloride at low temperatures; either the threo or the erythro aldol products can be obtained. An asymmetric epoxidation permitted a subsequent highly enantiocontrolled semi-pinacol rearrangement.

Kinetic resolution via semipinacol rearrangement of α-hydroxy epoxides: a new method for asymmetric synthesis of α-hydroxy epoxides and β-hydroxy ketones containing an α-quaternary carbon

A new method for the enantioselective preparation of β-hydroxy ketones containing a stereogenic quaternary carbon center and tertiary α-hydroxy epoxides has been developed on the basis of kinetic resolution of racemic tertiary α-hydroxy epoxide via semipinacol rearrangement using the chiral catalyst Ti-[( R)/( S)-BINOL] 2. The effect of the structure of the migrating group on the enantioselectivity of the reaction is also discussed.

Simple access to novel β-hydroxy-β-trifluoromethyl imines

Selected imines reacted with three different trifluoromethyl group-containing ketones in a non-catalyzed manner at ambient temperature to give the corresponding β-hydroxy-β-trifluoromethyl imines in good to excellent yields. With 1,1,1-trifluoroacetone a 1:1 and a 2:1 reaction product was obtained. The reduction of 2-isopropylimino-4-phenyl-5,5,5-trifluoropentan-4-ol led to a 5:1 diastereomeric mixture of the corresponding amine, whose dominant form was found to be ( 2S, 4R) 4-isopropylamino-4-phenyl-2-trifluoromethyl-butan-2-ol in the solid state. Hydrolysis in one case gave the respective β-hydroxy ketone.

A Highly Diastereoselective TiCl4-Mediated Reduction of β-Hydroxy Ketones with BH3·py — A Very Efficient and General Synthesis of syn-1,3-Diols

β-Hydroxy ketones can be reduced to the corresponding 1,3-diols in high yields and with excellent diastereoselectivity by carrying out the reaction with BH3·pyridine in CH2Cl2 at −78 °C in the presence of TiCl4. This protocol is general and chemoselective: excellent results are obtained when the substituents are primary, secondary, tertiary alkyl chains or aromatic moieties. The presence of reducible functionalities such as bromide, nitro and cyano groups is well tolerated.

Reformatsky-type reaction of α-haloketones promoted by titanium tetraiodide

Titanium(IV) tetraiodide induces a Reformatsky-type reaction of α-iodoketones with carbonyl compounds to give β-hydroxy ketones in good to high yields.

The Story of Lescol: From Research to Production

Process R&D transformed a research synthesis of fluvastatin into a commercial process. The major hurdle in the synthesis was the stereoselectivity of the syn-diol formation. The problem was attacked and solved from three directions. First, a method was developed that separated the syn and anti isomers that did not require chromatography. Second, a new, totally stereoselective synthesis, starting with phloroglucinol, was designed to produce the side-chain containing the syn-diol. And third, a new and general stereoselective reaction was invented for the reduction of β-hydroxy ketones to syn-diols. The 99% syn-selectivity of this reaction was achieved with sodium borohydride as the reducing agent, diethylmethoxyboron as the chelating agent, and tetrahydrofuran and methanol as solvents in a 4:1 ratio, at −70 °C. The final process was only six steps long, entirely stereoselective in both the E-olefin and syn-diol formation, and required no chromatography. The cost of the synthesis was thus reduced by a factor...

A mild and chemoselective method for the reduction of conjugated isoxazolines to beta-hydroxy ketones.

A new procedure for the selective reduction of conjugated Delta(2)-isoxazolines to the corresponding unsaturated beta-hydroxy ketones is described. The use of SmI(2) as the reducing agent and B(OH)(3) to hydrolyze the resulting imine results in a mild, convenient, and chemoselective protocol for this otherwise difficult transformation and complements existing methodology for the preparation of beta-hydroxy ketones via nitrile oxides.

Stereoselective synthesis of tetrahydrofurans: reactions of protected β-hydroxy ketones with benzyl diazoacetate

The stereoselective synthesis of 2,3,3,4-tetrasubstituted tetrahydrofurans from the Lewis acid catalyzed reaction of protected β-hydroxy ketones with benzyl diazoacetate is described. The reaction can be used to set three contiguous stereocenters including one that is a tertiary alcohol.

ASYMMETRIC OXIDATION OF KETONES

The Ti(OiPr)4/tartaric acid diethyl ester/ t-BuOOH complex (Sharpless catalyst) was successfully used for the direct asymmetric oxidation of ketones resulting in lactones from cyclobutanones; α ,β-dihydroxy ketones from β-hydroxy ketones; alkyl lactone carboxylic acids from 3-alkylcyclopentane-1,2-diones; and spiro-γ-dilactone from 3-(2-hydroxyethyl)cyclopentane- 1,2-dione in high enantioselectivity and satisfactory yield.

The semi-pinacol rearrangement of homochiral epoxyalcohols catalysed by rare earth triflates

α,β-Epoxy ketones, prepared using the polyleucine catalysed asymmetric epoxidation of enones, can be converted into α-substituted β-hydroxy ketones via carbonyl alkylation with Grignard reagents followed by ytterbium triflate catalysed semi-pinacol rearrangement of the resulting epoxyalcohols.

ChemInform Abstract: Synthesis of β-Hydroxy Ketones and Vinylsilanes from Homopropargylic Alcohols by Intramolecular Hydrosilylation.

ChemInform 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: An Efficient Procedure for the Diastereoselective Dehydration of β-Hydroxy Carbonyl Compounds by CeCl3×7H2O/NaI System.

The dehydration of β-hydroxy ketones and β-hydroxy esters is a synthetically useful method for the conversion of these compounds to the corresponding α,β-unsaturated derivatives. Cerium(III) chloride heptahydrate in combination with sodium iodide in refluxing acetonitrile acts as an efficient reagent for this conversion. The present procedure, which utilizes cheap and “friendly” reagents, offers the corresponding (E)-enones in good yields as the only isolable products.

Lipase catalyzed kinetic resolution of aryl β-hydroxy ketones

Enzymatic kinetic resolution of racemic aryl β-hydroxy ketones in organic media catalyzed by Candida cylindracea lipase is reported.

Oxazole–Carbonyl photocycloadditions: selectivity pattern and synthetic route to erythro α-amino, β-hydroxy ketones

Download options Please wait... Supplementary files Crystal data TXT (13K) Article information DOI https://doi.org/10.1039/B000578I Article type Communication Submitted 20 Jan 2000 Accepted 23 Feb 2000 First published 20 Mar 2000 Download Citation Chem. Commun., 2000, 589-590 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Oxazole–Carbonyl photocycloadditions: selectivity pattern and synthetic route to erythro α-amino, β-hydroxy ketones A. G. Griesbeck, M. Fiege and J. Lex, Chem. Commun., 2000, 589 DOI: 10.1039/B000578I To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Axel G. Griesbeck Maren Fiege Johann Lex

Zinc bromide as catalyst for the stereoselective construction of quaternary carbon: improved synthesis of diastereomerically enriched spirocyclic diols

Zinc bromide (ZnBr2) has proved to be a facile and efficient catalyst for the stereoselective semipinacol rearrangement of α-hydroxy epoxides at room temperature. Of note are the presence in the product of two adjacent chiral carbon centers, particularly the creation of a stereoselective quaternary center, and the efficient synthesis of β-hydroxy ketones, including some with naturally occurring spiroalkane skeletons. As an example of its application, important diastereomerically enriched spirocyclic diol ligands have been synthesized conveniently via this rearrangement followed by reduction of the spirocyclic β-hydroxy ketones obtained with appropriate hydride reagents.

Studies Directed Toward the Synthesis of Taxanes: Construction of the Tricyclo[5.3.1.01,7]undecane System

The intramolecular nucleophilic substitution of an epoxide by the anion of a nitrile was used to construct the bicyclo[3.1.0]hexane system of 9, derived from 8, and of 14, derived from 13. The intramolecular 1,3-dipolar cycloaddition of nitrile oxide 4, obtained from 14, led to isoxazoline 3. However, it was not possible to convert 3 into the corresponding β-hydroxy ketone. Rearrangements of 3 were observed in the presence of dehydrating reagents leading to compounds 19–21, which are structurally related to 11(15→1)abeotaxanes.

Studies Directed Toward the Synthesis of Taxanes: Construction of the Tricyclo[5.3.1.01,7]undecane System

The intramolecular nucleophilic substitution of an epoxide by the anion of a nitrile was used to construct the bicyclo[3.1.0]hexane system of 9, derived from 8, and of 14, derived from 13. The intramolecular 1,3-dipolar cycloaddition of nitrile oxide 4, obtained from 14, led to isoxazoline 3. However, it was not possible to convert 3 into the corresponding β-hydroxy ketone. Rearrangements of 3 were observed in the presence of dehydrating reagents leading to compounds 19–21, which are structurally related to 11(15→1)abeotaxanes.

A Novel Approach to the Synthesis of Optically Active Poly(β-hydroxy carbonyl)s by Aldol Polymerization Based on Mukaiyama Aldol Reaction

We have synthesized the poly(β-hydroxy ketone)s 1 and poly(β-hydroxy ester)s 2 by means of a novel polyaddition reaction of bis(triethylsilyl enol ether) 5 and bis(triethylsilyl ketene acetal) 7 with various dialdehydes 8–10, respectively. When chirally modified Lewis acids were used as catalyst for the polyaddition, optically active polymers were obtained.

Novel Poly(vinyl alcohol)-Degrading Enzyme and the Degradation Mechanism

A novel poly(vinyl alcohol) (PVA) degradation pathway was demonstrated such that the hydroxy group of PVA was first dehydrogenated into the corresponding carbonyl group to form the β-hydroxy ketone moiety which was followed by the aldolase-type cleavage to produce the methyl ketone and the aldehyde terminals by the PVA-assimilating strain, Alcaligenes faecalis KK314. Both the biodegradation steps of dehydrogenation and subsequent aldolase-type cleavage were catalyzed by the same protein having 67 kDa as the holoenzyme and apoenzyme of PVA dehydrogenase, respectively.

A new route to (2 S,4 R)- and (2 R,4 S)-4-hydroxypipecolic acid

Both enantiomers of cis-4-hydroxypipecolic acid have been prepared by asymmetric synthesis using ( S)- or ( R)-glycidol as the chiral source, and involving a stereoselective hydrogenation of a six-membered cyclic imine. The latter is obtained by reduction and cyclization of a cyano β-hydroxy ketone.