- Preparation method of 3, 3-dimethyl-2-oxobutyric acid and triazinone
-
The invention relates to the field of pesticides, and discloses a preparation method of 3, 3-dimethyl-2-oxobutyric acid and triazinone. The preparation method of the 3, 3-dimethyl-2-oxobutyric acid provided by the invention comprises the step of oxidizing the 3, 3-dimethyl-2-oxobutyric acid and/or a salt thereof by taking oxygen-containing gas as an oxidizing agent in the presence of a catalyst under the condition that the pH value is 7-13. According to the method disclosed by the invention, the 3, 3-dimethyl-2-hydroxybutyric acid and/or the salt thereof is taken as the raw material, and oxygen or air is used for replacing other oxidants, so that high-salinity wastewater and solid waste are avoided, the cost of the raw material is reduced, and the method is simple to operate and suitable for industrial production.
- -
-
Paragraph 0055-0056; 0058-0059; 0061-0062; 0064-0065; 0067
(2021/06/23)
-
- Stereoselective Modification of N-(α-Hydroxyacyl)-glycinesters via Palladium-Catalyzed Allylic Alkylation
-
N-(α-Hydroxyacyl)-glycinesters can be used as excellent nucleophiles in Pd-catalyzed allylic alkylation. The method allows for the stereoselective introduction of a wide range of side chains, including highly functionalized ones. Both diastereomers can be accessed through variation of the reaction conditions. Furthermore, the use of stannylated carbonates introduces vinylstannane motifs, which are eligible for subsequent C-C coupling reactions.
- Horn, Alexander,Kazmaier, Uli
-
supporting information
p. 4595 - 4599
(2019/06/27)
-
- Preparation method of 3,3-dimethyl-2-oxobutyric acid
-
The invention relates to a preparation method of 3,3-dimethyl-2-oxobutyric acid, and belongs to the technical field of pharmaceutical intermediate synthesis. In order to solve the problems of seriouspollution and low yield of the existing synthetic route, the invention provides a preparation method of 3,3-dimethyl-2-oxobutyric acid, and the method comprises: halogenating 3,3-dimethyl butyric acidwith a halogenating agent in an organic solvent to obtain an intermediate product; then carrying out a hydrolysis reaction to obtain a corresponding hydrolyzed product; and in the presence of TEMPO catalyst, oxidizing the hydrolyzed product under the action of an oxidant, and then carrying out acidification to obtain a product 3,3-dimethyl-2-oxobutyric acid. According to the preparation method provided by the invention, a mixed catalyst of a noble metal catalyst and a transition metal catalyst is avoided, the environmental pollution and the cost are reduced, and the effects of high yield andhigh purity can still be ensured.
- -
-
Paragraph 0035; 0037
(2018/10/04)
-
- Readily Accessible 1,2-Amino Ether Ligands for Enantioselective Intramolecular Carbolithiation
-
A new class of chiral 1,2-amino ether ligands, readily accessible from naturally occurring α-amino- or α-hydroxy acids, was found to provide high levels of both conversion and stereocontrol (up to 95:5 er) in intramolecular carbolithiation reactions, outperforming the benchmark ligand (?)-sparteine. The ligand could be used in a substoichiometric amount (0.25 equiv) without significant loss of enantioselectivity.
- Guyon, Hélène,Boussonnière, Anne,Castanet, Anne-Sophie
-
p. 4949 - 4957
(2017/05/12)
-
- Janadolide, a Cyclic Polyketide-Peptide Hybrid Possessing a tert-Butyl Group from an Okeania sp. Marine Cyanobacterium
-
Janadolide, a new cyclic polyketide-peptide hybrid possessing a tert-butyl group, was isolated from an Okeania sp. marine cyanobacterium. The gross structure was elucidated by spectroscopic analyses, and the absolute configurations of the amino acid moieties were determined by acid hydrolysis and chiral-phase HPLC analyses. The absolute configuration of the two stereogenic centers in the polyketide moiety was elucidated based on a combination of degradation reactions and spectroscopic analyses including the phenyl-glycine methyl ester method. Janadolide showed potent antitrypanosomal activity with an IC50 value of 47 nM without cytotoxicity against human cells at 10 μM.
- Ogawa, Hidetoshi,Iwasaki, Arihiro,Sumimoto, Shinpei,Kanamori, Yuki,Ohno, Osamu,Iwatsuki, Masato,Ishiyama, Aki,Hokari, Rei,Otoguro, Kazuhiko,Omura, Satoshi,Suenaga, Kiyotake
-
p. 1862 - 1866
(2016/08/02)
-
- Asymmetric hydrogenation reaction of alpha-ketoacids compound
-
The invention relates to the technical field of organic chemistry, especially to an asymmetric hydrogenation reaction of an alpha-ketoacids compound. The asymmetric hydrogenation reaction comprises a scheme shown in the description. In the scheme, R1 is phenyl, substituted phenyl, naphthyl, substituted naphthyl, C1-C6 alkyl, or aralkyl; a substituent group is C1-C6 alkyl, C1-C6 alkoxy, or halogen; and the number of the substituent group is 1-3. In the scheme, M is a chiral spiro-pyridylamino phosphine ligand iridium complex having a structure shown in the description. In the structure, R is hydrogen, 3-methyl, 4-tBu, or 6-methyl.
- -
-
Paragraph 0037; 0044
(2016/10/10)
-
- Metal-free one-pot α-carboxylation of primary alcohols
-
An efficient metal-free procedure for the formal α-carboxylation of primary alcohols has been developed. The method involves a one-pot oxidation/Passerini/hydrolysis sequence and provides access to α-hydroxy acids bearing a broad range of functional groups. A minor modification to the reaction conditions extends the range of accessible products to α-hydroxy esters.
- Van Der Heijden, Gydo,Kraakman, Jasper,Biemolt, Jasper,Ruijter, Eelco,Orru, Romano V. A.
-
supporting information
p. 9716 - 9719
(2016/10/31)
-
- Chiral propargylic cations as intermediates in SN1-type reactions: Substitution pattern, nuclear magnetic resonance studies, and origin of the diastereoselectivity
-
Nine propargylic acetates, bearing a stereogenic center (-C*HXR 2) adjacent to the electrophilic carbon atom, were prepared and subjected to SN1-type substitution reactions with various silyl nucleophiles employing bismuth trifluoromethanesulfonate [Bi(OTf)3] as the Lewis acid. The diastereoselectivity of the reactions was high when the alkyl group R2 was tertiary (tert-butyl), irrespective of the substituent X. Products were formed consistently with a diastereomeric ratio larger than 95:5 in favor of the anti-diastereoisomer. If the alkyl substitutent R2 was secondary, the diastereoselectivity decreased to 80:20. The reaction was shown to proceed stereoconvergently, and the relative product configuration was elucidated. The reaction outcome is explained by invoking a chiral propargylic cation as an intermediate, which is preferentially attacked by the nucleophile from one of its two diastereotopic faces. Density functional theory (DFT) calculations suggest a preferred conformation in which the group R2 is almost perpendicular to the plane defined by the three substituents at the cationic center, with the nucleophile approaching the electrophilic center opposite to R2. Transition states calculated for the reaction of allyltrimethylsilane with two representative cations support this hypothesis. Tertiary propargylic cations with a stereogenic center (-C* HXR2) in the α position were generated by ionization of the respective alcohol precursors with FSO3H in SO2ClF at -80 C. Nuclear magnetic resonance (NMR) spectra were obtained for five cations, and the chemical shifts could be unambiguously assigned. The preferred conformation of the cations as extracted from nuclear Overhauser experiments is in line with the preferred conformation responsible for the reaction of the secondary propargylic cations.
- Nitsch, Dominik,Huber, Stefan M.,Poethig, Alexander,Narayanan, Arjun,Olah, George A.,Prakash, G. K. Surya,Bach, Thorsten
-
p. 2851 - 2857
(2014/03/21)
-
- Direct asymmetric hydrogenation of α-keto acids by using the highly efficient chiral spiro iridium catalysts
-
A new efficient and highly enantioselective direct asymmetric hydrogenation of α-keto acids employing the Ir/SpiroPAP catalyst under mild reaction conditions has been developed. This method might be feasible for the preparation of a series of chiral α-hydroxy acids on a large scale.
- Yan, Pu-Cha,Xie, Jian-Hua,Zhang, Xiang-Dong,Chen, Kang,Li, Yuan-Qiang,Zhou, Qi-Lin,Che, Da-Qing
-
supporting information
p. 15987 - 15990
(2015/02/19)
-
- Reaction intermediate analogues as bisubstrate inhibitors of pantothenate synthetase
-
The biosynthesis of pantothenate, the core of coenzyme A (CoA), has been considered an attractive target for the development of antimicrobial agents since this pathway is essential in prokaryotes, but absent in mammals. Pantothenate synthetase, encoded by the gene panC, catalyzes the final condensation of pantoic acid with β-alanine to afford pantothenate via an intermediate pantoyl adenylate. We describe the synthesis and biochemical characterization of five PanC inhibitors that mimic the intermediate pantoyl adenylate. These inhibitors are competitive inhibitors with respect to pantoic acid and possess submicromolar to micromolar inhibition constants. The observed SAR is rationalized through molecular docking studies based on the reported co-crystal structure of 1a with PanC. Finally, whole cell activity is assessed against wild-type Mtb as well as a PanC knockdown strain where PanC is depleted to less than 5% of wild-type levels.
- Xu, Zhixiang,Yin, Wei,Martinelli, Leonardo K.,Evans, Joanna,Chen, Jinglei,Yu, Yang,Wilson, Daniel J.,Mizrahi, Valerie,Qiao, Chunhua,Aldrich, Courtney C.
-
p. 1726 - 1735
(2014/03/21)
-
- MACROCYCLIC INHIBITORS OF FLAVIVIRIDAE VIRUSES
-
Provided are compounds of Formula I and pharmaceutically acceptable salts and esters thereof. The compounds, compositions, and methods provided are useful for the treatment of virus infections, particularly hepatitis C infections.
- -
-
Page/Page column 261
(2014/01/08)
-
- Camphor-based Schiff base ligand SBAIB: An enantioselective catalyst for addition of phenylacetylene to aldehydes
-
A series of Schiff base ligands were synthesized from (1R)-camphor. Under the optimal conditions, (+)-SBAIB-a, 10 was found to be an excellent catalyst for the enantioselective addition of phenylacetylene to various aldehydes without utilizing either achiral additives or Ti(OiPr)4. This approach yielded (R)-propargylic alcohols in extremely high yields (up to 99%) and excellent enantioselectivities (up to 92%). The corresponding (S)-propargylic alcohols were synthesized in good to high enantioselectivities (up to 91%) and excellent yields (up to 99%) using (-)-SBAIB-a, 41.
- Boobalan, Ramalingam,Chen, Chinpiao,Lee, Gene-Hsian
-
scheme or table
p. 1625 - 1638
(2012/03/22)
-
- Stereospecific α-methallylation of hydroxyaldehydes by silatropic ene cyclisation
-
We describe the thermal rearrangement of aldehydes bearing an α-(allyl- or crotylsilyl)oxy substituent. The transformations are best described mechanistically as intramolecular silatropic ene reactions based on stereoselectivity, kinetic and computed transition state data. The overall process constitutes a stereospecific (meth)allylation of α-hydroxyaldehydes, under neutral conditions, in which the hydroxyl protecting group is also the (meth)allylating agent.
- Robertson, Jeremy,Hall, Michael J.,Green, Stuart P.
-
experimental part
p. 5541 - 5551
(2009/12/09)
-
- The design and synthesis of inhibitors of pantothenate synthetase
-
Pantothenate synthetase catalyses the ATP-dependent condensation of d-pantoate and β-alanine to form pantothenate. Ten analogues of the reaction intermediate pantoyl adenylate, in which the phosphodiester is replaced by either an ester or sulfamoyl group, were designed as potential inhibitors of the enzyme. The esters were all modest competitive inhibitors, the sulfamoyls were more potent, consistent with their closer structural similarity to the pantoyl adenylate intermediate. The Royal Society of Chemistry 2006.
- Tuck, Kellie L.,Saldanha, S. Adrian,Birch, Louise M.,Smith, Alison G.,Abell, Chris
-
p. 3598 - 3610
(2008/10/09)
-
- P2-P3 conformationally constrained ketoamide-based inhibitors of cathepsin K
-
An orally bioavailable series of ketoamide-based cathepsin K inhibitors with good pharmacokinetic properties has been identified. Starting from a potent inhibitor endowed with poor drug properties, conformational constraint of the P2-P3 linker and modifications to P1′ elements led to an enhancement in potency, solubility, clearance, and bioavailability. These optimized inhibitors attenuated bone resorption in a rat TPTX hypocalcemic bone resorption model.
- Barrett, David G.,Boncek, Virginia M.,Catalano, John G.,Deaton, David N.,Hassell, Anne M.,Jurgensen, Cynthia H.,Long, Stacey T.,McFadyen, Robert B.,Miller, Aaron B.,Miller, Larry R.,Payne, J. Alan,Ray, John A.,Samano, Vicente,Shewchuk, Lisa M.,Tavares, Francis X.,Wells-Knecht, Kevin J.,Willard Jr., Derril H.,Wright, Lois L.,Zhou, Hui-Qiang Q.
-
p. 3540 - 3546
(2007/10/03)
-
- Stereoselective synthesis of a potent thrombin inhibitor by a novel P2-P3 lactone ring opening
-
The concise synthesis of a potent thrombin inhibitor was accomplished by a mild lactone aminolysis between an orthogonally protected bis-benzylic amine and a diastereomerically pure lactone. The lactone was synthesized by the condensation of L-proline met
- Nelson, Todd D.,LeBlond, Carl R.,Frantz, Doug E.,Matty, Louis,Mitten, Jeffrey V.,Weaver, Damian G.,Moore, Jeffrey C.,Kim, Jaehon M.,Boyd, Russell,Kim, Pei-Yi,Gbewonyo, Kodzo,Brower, Mark,Sturr, Michael,McLaughlin, Kathleen,McMasters, Daniel R.,Kress, Michael H.,McNamara, James M.,Dolling, Ulf H.
-
p. 3620 - 3627
(2007/10/03)
-
- N-heterocyclic bicyclic lactone compounds
-
Novel N-heterocyclic bicyclic lactone compounds of formula I and its novel hydroxyamide precursors of formula IV, are synthesized by coupling a hydroxy acid of formula II with an ester of formula III or a pharmaceutically acceptable salt thereof, in the presence of a peptide coupling reagent to produce a hydroxyamide of formula IV, and cyclizing the hydroxyamide of formula IV to produce compounds of formula 1.
- -
-
-
- α-Hydroxy carboxylic acids as ligands for enantioselective diethylzinc additions to aromatic and aliphatic aldehydes
-
The first examples of the enantioselective titanium-mediated diethylzinc additions to aromatic and aliphatic aldehydes catalyzed by optically active α-hydroxy acids are presented. The reactions proceed with very good yield and good asymmetric induction. Enantioselectivities up to 90% are obtained depending on ligand and aldehyde used. A stereochemical model for the reaction is proposed.
- Bauer, Tomasz,Gajewiak, Joanna
-
p. 9163 - 9170
(2007/10/03)
-
- 1,3-Diastereocontrol in acyclic radical allylations
-
The radical allylation of an acyclic α-hydroxyketone with allyltributyltin under chelation-controlled conditions is reported. Several reaction conditions were explored, including radical initiators, solvents, and temperatures to improve the yield and the diastereomeric ratio. Some Lewis acids, like magnesium bromide etherate and zinc chloride, gave superior diastereomeric ratios (up to 100:1) and good yields.
- Enholm, Eric J.,Lavieri, Sophie,Cordóva, Tanya,Ghiviriga, Ion
-
p. 531 - 534
(2007/10/03)
-
- Thrombin inhibitors
-
Compounds of the invention are useful in inhibiting thrombin and associated thrombotic occlusions having the following structure: or a pharmaceutically acceptable salt thereof, e.g. 1-(3(S)-Cyclopropyl-2(R)-hydroxybutanoyl)azetidine-2(S)-N-(2-aminomethyl-5-chlorobenzyl)carboxamide, and 1-(3-Cyclopropyl-3-methyl-2(R)-hydroxybutanoyl)azetidine-2(S)-N-(2-aminomethyl-5-chlorobenzyl)carboxamide.
- -
-
-
- Thrombin inhibitors
-
Compounds of the invention are useful in inhibiting thrombin and associated thrombotic occlusions having the following structure: or a pharmaceutically acceptable salt thereof, e.g. 1-(3(S)-Cyclopropyl-2(R)-hydroxybutanoyl)azetidine-2(S)-N-(2-aminomethyl-5-chlorobenzyl)carboxamide, and 1-(3-Cyclopropyl-3-methyl-2(R)-hydroxybutanoyl)azetidine-2(S)-N-(2-aminomethyl-5-chlorobenzyl)carboxamide.
- -
-
-
- Lithiated camphor-derived oxazolidinone S,N-acetals as chiral formyl anion synthons in additions to aldehydes. Asymmetric synthesis of α-hydroxy aldehydes and α-hydroxy acids
-
N-(Phenylthiomethyl)oxazolidinones derived from camphor can be lithiated and added to aldehydes in good yields and stereoselectivities. The adducts are crystalline, which simplifies isolation of the major diastereomer from the product mixture. Hydrolysis affords enantiopure α-hydroxy aldehydes, which can be oxidized to α-hydroxy acids in good yields. The steric course of the reaction is analyzed in detail and a mechanistic model is presented.
- Gawley, Robert E.,Campagna, Silvio A.,Santiago, Marcelina,Ren, Tong
-
-
- Thrombin inhibitors
-
Compounds of the invention are useful in inhibiting thrombin and associated thrombotic occlusions having the following structure: or a pharmaceutically acceptable salt thereof, e.g. where R3 is —CH2NH2, —CH2CH2NH2, or —CH2NHC(O)OC(CH3)3.
- -
-
-
- Enantioseparation of racemic organic ammonium perchlorates by a silica gel bound optically active di-tert-butylpyridino-18-crown-6 ligand
-
Both enantiomers of the novel chiral di-tert-butylpyridino-18-crown-6 ligand (R,R)-7 and (S,S)-7 containing an allyloxy group on the pyridine subcyclic unit were prepared by the reaction of 4-allyloxy-2,6-pyridinedimethyl ditosylate 9 and the enantiomers of di-tert-butyl-substituted tetraethylene glycol (R,R)-8 and (S,S)-8 in the presence of a strong base. One of them, (R,R)-7, was covalently attached to silica gel, and this chiral stationary phase (CSP) separated four selected racemic organic ammonium perchlorates into their enantiomers by column chromatography.
- Koentoes, Zoltan,Huszthy, Peter,Bradshaw, Jerald S.,Izatt, Reed M.
-
p. 2087 - 2100
(2007/10/03)
-
- Reaction of carboxylic acids with diethyl phosphorocyanidate; a novel synthesis of homologated α-hydroxycarboxylic acids from carboxylic acids
-
Carboxylic acids react with 2 equivalents of diethyl phosphorocyanidate in the presence of triethylamine to give dicyanophosphates in good yields; these dicyanophosphates can be hydrolyzed easily to give homologated α- hydroxycarboxylic acids.
- Mizuno, Masanori,Shioiri, Takayuki
-
p. 9209 - 9210
(2007/10/03)
-
- Polyfunctional (R)-2-Hydroxycarboxylic Acids by Reduction of 2-Oxo Acids with Hydrogen Gas or Formate and Resting Cells of Proteus vulgaris
-
Various (R)-2-hydroxy acids such as (R)-2-hydroxy-3-enoic-, 3,5-dienoic-, 4-oxo-, (R,S)-3-hydroxy and some others were prepared on a scale up to 0.12 mol by biocatalytic reduction of the corresponding 2-oxo acids with P. vulgaris and hydrogen gas and/or formate as electron donors.With the exception of the 2-hydroxy-4-oxo acids it could be proved that the enantiomeric excess is >97 percent.For the 4-oxo derivatives this enantiomeric excess can be assumed.The yields of isolated products are high because they were isolated from rather small amounts of biocatalyst and low buffer concentrations.Product concentrations in the range of 0.1- 0.24 M were obtained.For 1 mmol of product formation in 15-20 h about 20-40 mg (dry weight) of P. vulgaris cells are necessary.
- Schummer, Anita,Yu, Hongtao,Simon, Helmut
-
p. 9019 - 9034
(2007/10/02)
-
- Synthesis of a Chiral, Nonracemic Aziridinone (α-Lactam)
-
(S)-tert-Leucine is diazotized affording a mixture of the expected α-chloro and α-hydroxy acids (S)-15 and (S)-16 and the rearranged β-chloro and β-hydroxy acids (R)-12 and (S)-11.Separation produces a 51percent yield of pure (S)-15 (e.e. >= 97.4percent) which is converted via the acid chloride (S)-17 into the α-chloro amides (S)-18a and b (e.e. = 99.0 and 95.2percent, respectively).On treatment with tBuOK, the latter is converted into the α-lactam (R)-22b (59percent, e.e. >= 91.0percent, D20 = -293.7), which is accompanied by small amounts of its ring opening product (R)-23b.Only the α-amino ester (R)-23a is formed from the α-chloro amide (S)-18a and tBuOK.While the enantiomers of the halo amides 13, 18a, b, 24a, b and of the 3-pentyl esters of the hydroxy acid 16 are separated by GC on chiral columns, the α-lactam 22b and the α-amino esters 23a, b require conversion into separable derivatives without involving the stereogenic center.Thus, alkaline hydrolysis of 22b as well as acidic cleavage of 23 yield the α-amino acids 25 which are cyclized to the oxazolidine-2,5-diones 26 by means of bis(trichloromethyl)carbonate ("triphosgene").As shown by the high enantiomeric excess of the products derived from (S)-tert-leucine none of the reactions described results in a considerable degree of racemization.Authentic samples of 11 and 12 are synthesized from the Reformatzky product 21.The absolute configurations of the major enantiomers derived from (S)-14 are based on the retention on chiral GC columns, the signs of optical rotations, and CD spectra.The mechanism of the rearrangement leading to the β-hydroxy and β-chloro acids (S)-11 and (R)-12 is interpreted in terms of a stereospecific 1,2-methyl shift occurring simultaneously with the ring cleavage of the (protonated) α-lactone (R)-2 (R = tBu) which is the crucial intermediate formed in the diazotization of (S)-14.
- Quast, Helmut,Leybach, Holger
-
p. 849 - 859
(2007/10/02)
-
- Protocols for the Preparation of Each of the Four Possible Stereoisomeric α-Alkyl-β-hydroxy Carboxylic Acids from a Single Chiral Aldol Reagent
-
Protocols have been devised whereby all four possible stereoisomeric α-alkyl-β-hydroxy carboxylic acids can be derived from a single aldol reagent, hydroxy ketone 3.Compound 3, obtained in enantiomerically homogeneous form in 50percent overall yield from tert-butylglycine (1), is used for aldol reactions in the form of its trimethylsilyl and tert-butyldimethylsilyl derivatives, 4 and 5.The Z lithium and Z boron enolates of 4 react with various aldehydes to give aldols 8 and 9, respectively.Deprotonation of 4 by bromomagnesium 2,2,6,6-tetramethylpiperidide (MTMP) gives the E enolate, which may be trapped by trimethylsilyl chloride to obtain the E silyl enol ether 11.The E bromomagnesium enolate of 4 reacts with aldehydes to give aldols of structure 15.Transmetalation of the bromomagnesium enolate of keto ether 5 is accomplished by reaction with (triisopropoxy)titanium chloride.The resulting E (triisopropoxy)titanium enolate reacts with aldehydes to provide aldols of structure 17.The aldols resulting from the foregoing reactions are hydrolyzed to keto diols 19-22, which are oxidized to the stereoisomeric α-methyl-β-hydroxy carboxylic acids 23-26.
- Draanen, Nanine A. Van,Arseniyadis, Simeon,Crimmins, Michael T.,Heathcock, Clayton H.
-
p. 2499 - 2506
(2007/10/02)
-
- Synthesis of Trialkylacetic Acids by the Anodic Oxidation of 3,3-Disubstituted-2-oxo Carboxylic Acids
-
The "non-Kolbe" electrolysis of 3,3-disubstituted-2-oxocarboxylates 1-3 in methanol produced mixtures of methyl trialkylacetates 5, trialkylacetaldehydes 6, in some cases 2-hydroxy-3,3,3-trialkylpropionic acids 7, trialkylethylenes 8, and methyl trialkylmethyl ethers 9.When one of the substituents on the 3-carbon of the 2-oxo carboxylate was phenyl 4, molecular rearrangement was not observed.In addition to products 5-9, with the exception of 7, there was obtained with 4 an alkyl phenyl ketone 10.The methyl trisubstituted acetates were saponified to the desired trialkylacetic acids.
- Rabjohn, Norman,Cranor, W. L.,Schofield, C. M.
-
p. 1732 - 1736
(2007/10/02)
-
- Regioselective Lewis Acid-mediated α-tert-Alkylation of Acyloins and Glycolic Acid
-
O,O'-Bis-silylated acyloins 10a-h as well as the tris-silylated form 13 of glycolic acid (7) can be tert-alkylated with tert-butyl chloride or 1-adamantyl bromide in the presence of catalytic amounts of ZnCl2.In case of unsymmetrically substituted derivatives, complete regioselectivity according to the Markovnikov rule is observed.The adamantylated acyloins are converted into α,β-unsaturated α-adamantyl ketones 27-30 upon treatment with H2SO4.
- Reetz, Manfred T.,Heimbach, Horst
-
p. 3702 - 3707
(2007/10/02)
-
- Studies on the rearrangement of (trichloromethyl)carbinols to α-chloroacetic acids
-
Phenyl(trichloromethyl)carbinol undergoes an unimolecular, predominantly intramolecular conversion into potassium α-chlorophenylacetate on stirring with 10percent aqueous potassium hydroxide at 0 deg C for several days.Besides providing an interesting example of a 1-2 chlorine shift, the reaction is of potential importance for the synthesis of α-chloro acids.The study of a variety of (trichloromethyl)carbinols shows the reaction is general for secondary (trichloromethyl)carbinols as well as trichloroethanol.The mechanism of the reaction involves the preliminary formation of an epoxide.Several mechanisms are considered for the conversion of the epoxide to the α-chloroacetate anion, but none accounts for all of the experimental facts.Tertiary carbinols break down at the epoxide stage into a ketone and carbon monoxide.
- Reeve, Wilkins,McKee, James R.,Brown, Robert,Lakshmanan, Sitarama,McKee, Gertrude A.
-
p. 485 - 493
(2007/10/02)
-