23740-37-6Relevant academic research and scientific papers
Asymmetric synthesis of O-protected acyloins using enoate reductases: Stereochemical control through protecting group modification
Winkler, Christoph K.,Stueckler, Clemens,Mueller, Nicole J.,Pressnitz, Desiree,Faber, Kurt
supporting information; experimental part, p. 6354 - 6358 (2011/02/24)
O-Protected cyclic acyloins were obtained in nonracemic form through asymmetric bioreduction of α,β-unsaturated alkoxy ketones by using 11 different enoate reductases from the "Old Yellow Enzyme" family. The stereochemical outcome of the biotransformation could be switched by variation of the O-protecting group or by the ring size of the substrate, which allows access to both stereoisomers in up to >97 % ee Whereas α-alkoxy enones were readily accepted as substrates, β-analogs were not converted. Overall, α-alkoxy enones represent a novel type of substrate for flavin-dependent ene-reductases. Copyright
Ozonolysis of enol ethers. Part 10. Ozonization of enol ethers from 1,2- and 1,3-dicarbonyl compounds: Direct quantitative synthesis of phthalonic acid anhydride
Schank, Kurt,Beck, Horst,Pistorius, Susanne
, p. 2025 - 2049 (2007/10/03)
The results of ozonolyses of enol ethers from 1.2- and 1.3-dicarbonyl compounds presented here strongly indicate that these reactions do not proceed via the established Criegee ozonolysis mechanism for nucleophilic C=C bonds. The quantitative one-step synthesis of phthalonic acid anhydride via ozonolysis of 2-(methoxymethyliden)-1H-inden-1.3(2H)-dione (28a) is described. Furthermore, a revision of the theory of alkene ozonolysis in the presence of tetracyanoethylene (TCNE) is proposed on the basis of a single-electron-transfer (SET) chemistry.
Intramolecular 4+3 cycloadditions. A cyclohexenyl cation, its halogenated congener and a quasi-Favorskii rearrangement
Harmata, Michael,Bohnert, Gary,Kürti, Laszlo,Barnes, Charles L.
, p. 2347 - 2349 (2007/10/03)
Treatment of alkoxycyclohexenols bearing a tethered diene substituent with a Lewis acid results in intramolecular 4+3 cycloaddition with complete endo selectivity. A cycloadduct bearing a bromo substituent at a bridgehead position undergoes a quasi-Favorskii rearrangement in near quantitative yield upon reaction with lithium aluminum hydride.
Oxidation of 2-substituted cycloalkanones with cerium(IV) sulfate tetrahydrate in alcohols and acetic acid
He, Liangyou,Horiuchi, C. Akira
, p. 2515 - 2521 (2007/10/03)
The reaction of 2-substituted cycloalkanones with cerium(IV) sulfate tetrahydrate (CS) in alcohols and acetic acid gave the corresponding alkyl esters of oxo acids (80-96%) and oxo acids (78-96%), respectively, by oxidative cleavage of the C(R).C=O bond. In the case of 2-iodocycloalkanones in methanol, the dimethyl ester was obtained in good yield. A treatment of 5α-cholestan-3-one with CS in methanol produced 2-acetal 3-ester of 2,3-seco derivative in good yield. The effects of cerium(IV) and copper(II) salts are also discussed.
Biotransformation of αβ-unsaturated carbonyl compounds: sulfides, sulfoxides, sulfones, nitriles and esters by yeast species: carbonyl group and carbon-carbon double bond reduction
Koul, Surinder,Crout, David H. G.,Errington, William,Tax, Jiri
, p. 2969 - 2988 (2007/10/03)
The reduction of αβ-unsaturated ketones with γ-sulfide, sulfoxide, sulfone, nitrile and ester functions has been investigated.Both C=O and C=C reduction was observed.In the sulfur series, C=O bond reduction was always observed, but significant C=C bond reduction was observed only with the sulfide.The unsaturated nitriles gave the corresponding alcohols as the major bioreduction product, with smaller but significant amounts of fully reduced product.A similar result was obtained with the ester substrate.Relative and absolute configurations of bioreduction products were determined.A comparison was made between reductions catalysed by bakers' yeast (Saccharomyces cerevisiae) and by other yeasts (Zygosaccharomyces rouxii, Pichia capsulata, P. farinosa, Candida chalmersi and C. diddensiae).The tendency of Z. rouxii to give products enantiomeric with thouse obtained using S. cerevisiae was noted.The relationship between substrate structure and the stereochemistry of C=C double bond reduction is discussed.
α-Methoxylation of Unsaturated Carbonyl Compounds
Feuerer, Albert,Severin, Theodor
, p. 6026 - 6029 (2007/10/02)
α-Methoxylation of enals or enones can be performed in high yield by a simple one-pot reaction sequence: Bromination of unsaturated hydrazones, HBr-elimination, and addition of methanol leads to the formation of β-bromo-α-methoxy hydrazones (11), which af
Acid Catalyzed Alcoholysis of an Epoxide and Reactions of Products on Contact with Silica Gel
Habermehl, Gerhard G.,Wippermann, Irene
, p. 1421 - 1424 (2007/10/02)
The alcoholysis of epoxide 1 in acidic methanol leads to various products; one of these - hydroxymethoxyketone 7 - rearranges to the isomeric ketone 14 on contact with silica gel. Keywords: Cleavage of Epoxide, Rearrangement
Electrophilic β-Bromination and Nucleophilic α-Methoxylation of α,β-Unsaturated Carbonyl Compounds
Fischer, Hans,Klippe, Michael,Lerche, Holger,Severin, Theodor,Wanninger, Gabriele
, p. 399 - 404 (2007/10/02)
Oximes 29a,b, semicarbazones 11a-d, dimethylhydrazones 4, and hydrazones 23a-c of unsaturated aldehydes and ketones are brominated at the β-carbon by an addition-elimination sequence ( 21a,b, 13a-d, 7, and 27c, respectively.) When unsaturated ketone hydrazones are treated with bromine and methanol the α-methoxy-β-bromo derivatives 35a-c are obtained, which after hydrolysis and hydrobromic acid elimination give α-methoxy substitution products 36a-c of the starting compounds.
SYNTHESIS OF DIOSPHENOL ETHERS BY MEANS OF ALKOXYTRIMETHYLSILANES
Ponaras, A. A.,Meah, Md. Younus
, p. 4953 - 4956 (2007/10/02)
α-Diketones may be O-alkylated with a variety of alkoxytrimethylsilanes.
Reactions of α-Diazo Ketones with Selenium-based Reagents. A General Synthesis of α-Chloro-, α-Bromo, α-Phenylseleno-, α-Acetoxy-, and α-Methoxy-αβ-unsaturated Ketones
Buckley, Daniel J.,McKervey, M. Anthony
, p. 2193 - 2200 (2007/10/02)
Benzeneselenenyl derivatives, PhSe-X (X=Cl, Br, OCOCH3, and SCN) react readily with α-diazo ketones, RCOC(N2)R1 (R1=H or alkyl), with loss of nitrogen, furnishing αα-adducts of the type RCOCR1(X)SePh.The α-chloro and α-bromo adducts can be converted into α-methoxy adducts in methanol-sodium hydrogen carbonate.The utility of these adducts in synthesis is illustrated by their conversion (where structural considerations permit) via selenoxide fragmentation into α-heterosubstituted αβ-unsaturated ketones.Treatment of the series RCOCR1(X)SePh (R1=alkyl; X=Cl, Br, OCOCH3, and OCH3) with hydrogen peroxide-pyridine produces α-chloro-, α-bromo-, α-acetoxy-, and α-methoxy-αβ-unsaturated ketones, whereas treatment of series RCOCR1(X)SePh (R1=alkyl; X=Cl and Br) with lithium carbonate in dimethylformamide produces α-phenylseleno-αβ-unsaturated ketones.Several α-substituted cyclopentenones, cyclohexenones, and cycloheptenones have been synthesised in this way and acyclic examples are illustrated by the synthesis of 3-chloro-, 3-bromo-, 3-acetoxy-, 3-methoxy,-and 3-phenylselenobut-3-en-2-one from 3-diazobutan-2-one.
