- NEW ASSAYS FOR THE ENZYMATIC CONVERSION OF CHOLESTEROL TO PREGNENOLONE
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Cholesterol side chain cleavage is determined by means of separation of (26-14C)-cholesterol and its radioactively labeled side chain (1-14C)-isocaproic acid.Alumina minicolumn assay (AMCA): adsorption of cholesterol from an aqueous phase by aluminium oxide, while isocaproic acid can percolate through the column.In modification of a previously described technique, cholesterol is quantitatively eluted by ethanol.Filter assay (FA): retention of cholesterol by a membrane filter (pore size =/ 0.1 μm) while isocaproic acid can pass the filter.Two-phase scintillation assay (TPSA): pH-dependent partition of isocaproic acid between an organic scintillation mixture and an aqueous phase.The TPSA can be applied for all enzymatic reactions in which the polarity of the radioactive residue which is split off depends on pH values or when the total charge of apolar molecule is changed to an apolar state by cleaving one non-radioactive group (e.g. steroid sulfates) and vice versa.The criteria of reliability of the test systems are described.Bovine adrenal mitochondria were incubated and the side chain cleavage of (26-14C)-cholesterol was studied by the new test systems and compared to the conversion rates of (4-14C)-cholesterol to its metabolites as determined by thin layer chromatography.A good agreement of all tests was found.
- Rabe, T.,Rabe, D.,Bierwirth, A.-M.,Runnebaum, B.
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Read Online
- Strategic Approach to the Metamorphosis of γ-Lactones to NH γ-Lactams via Reductive Cleavage and C-H Amidation
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A new approach has elaborated on the conversion of γ-lactones to the corresponding NH γ-lactams that can serve as γ-lactone bioisosteres. This approach consists of reductive C-O cleavage and an Ir-catalyzed C-H amidation, offering a powerful synthetic tool for accessing a wide range of valuable NH γ-lactam building blocks starting from γ-lactones. The synthetic utility was further demonstrated by the late-stage transformation of complex bioactive molecules and the asymmetric transformation.
- Jung, Hoi-Yun,Chang, Sukbok,Hong, Sungwoo
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supporting information
p. 7099 - 7103
(2019/09/07)
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- Preparation method of carboxylic acid compound
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The invention provides a preparation method of a carboxylic acid compound. The preparation method comprises the following step of taking a lactone component to react with hydrogen in the presence of a compound catalyst to obtain the carboxylic acid compound. The compound catalyst comprises a hydrogenation catalyst and Lewis acid. In the presence of the compound catalyst comprising the hydrogenation catalyst and the Lewis acid, the lactone component is subjected to hydrogenation ring-opening reaction to obtain the carboxylic acid compound. The preparation method has the advantages of moderate reaction conditions and high yield; compared with a traditional method, less byproducts are generated, green and chemical requirements are met and the industrial value is better.
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Paragraph 0113; 0151-0153
(2017/08/29)
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- A Comprehensive Study on Metal Triflate-Promoted Hydrogenolysis of Lactones to Carboxylic Acids: From Synthetic and Mechanistic Perspectives
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Direct hydrogenolysis of lactone to carboxylic acid (i.e., hydrogenolysis of the Calkoxy-O bond with the carbonyl group untouched) is generally difficult, as the current strategies employing Br?nsted acids as the catalyst usually require harsh conditions such as a high temperature and a high H2 pressure. Herein, we report a developed solvent-free catalytic transformation, in which W(OTf)6 is believed to promote the hydrogenolysis process. This strategy could efficiently hydrogenate lactones to carboxylic acids under extra mild conditions (e.g., a reaction temperature of 2) and showed a broad substrate scope. In addition, the catalytic protocol can be further applied to the hydrogenolysis of polyhydroxyalkanoate, as a renewable polymer, to the corresponding straight-chain carboxylic acids. An extensive mechanistic study was subsequently performed, and the density functional theory calculations revealed a reaction pattern, including the complete cleavage of the C=O bond with the assistance of the W(OTf)6 catalyst. Moreover, the key intermediate created in the mechanism, as an oxonium with an OTf moiety, was successfully detected by electrospray ionization mass spectra. Through a comparison with the Br?nsted acid-catalyzed system, the study confirmed that the existence of the OTf moiety can significantly lower the barriers associated with the rearrangement and elimination processes. Meanwhile, emphasis was placed on the critical role that the anion plays, as well as the fact that the anion effect is directly related to the chemoselectivity.
- Zhu, Rui,Jiang, Ju-Long,Li, Xing-Long,Deng, Jin,Fu, Yao
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p. 7520 - 7528
(2017/11/10)
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- PROCESS FOR PRODUCING ALKANES USING MICROORGANISMS COMBINED WITH KOLBE SYNTHESIS
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The present invention relatesto a method of producing at least one alkane, the method comprising, -producing at least one carboxylic acid from a carbon source using a genetically modified microorganism, and -performing Kolbe electrolysis on the carboxylic acid to produce the alkane, wherein the alkane comprises at least 6 carbon atoms and the carboxylic acid comprises at least 4 carbon atomsand wherein the carbon source is selected from the group consisting of ethanol, acetate, propionate, butyrate, isobutyrate, valerate, hexanoate and combinations thereof and the microorganism is capable of producing the carboxylic acid using ethanol-carboxylate fermentation.
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Page/Page column 26; 27
(2016/02/26)
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- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
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The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
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The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- One-pot synthesis of micro/nano structured β-Bi2O3 with tunable morphology for highly efficient photocatalytic degradation of methylparaben under visible-light irradiation
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β-Bi2O3 micro/nanostructures with tunable morphologies were synthesized via a one-pot solvothermal-calcining route, and their photocatalytic activity toward degrading methylparaben (MeP, a widely used preservative with estrogenic activity) was evaluated under visible-light (λ ≥ 420 nm) irradiation. The formation process of β-Bi2O3 catalysts can be described as reduction of Bi3+ through a solvothermal reaction, followed by oxidization of metal Bi via calcination in air. During this process, the organic reductants (single or a mixture of ethylene glycol, d-fructose, and ascorbic acid) play important roles in determining the final morphologies and structures of the materials. Photocatalytic tests reveal that MeP can be effectively degraded and mineralized by using synthetic β-Bi2O3 catalysts, and the reaction rate constant of an optimum sample is more than 25 and 160 times faster than a commercial Bi2O3 and synthetic N-TiO2, respectively. The superior photocatalytic activity of the optimum product is ascribed to its pure beta phase with a narrower band gap, good absorption of visible light, more efficient separation of electrons and holes, relatively higher BET specific surface area, and three-dimensional architectures, which favor more surface active sites and easier mass and photoinduced charge transportations. In addition, the main reactive oxygen species and possible degradation intermediates were detected, and the results suggest that photogenerated holes and superoxide radicals are the predominant species in the photochemical oxidation process.
- Xiao, Xin,Hu, Ruiping,Tu, Shunheng,Zheng, Chunxia,Zhong, Huan,Zuo, Xiaoxi,Nan, Junmin
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p. 38373 - 38381
(2015/07/28)
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- Novel aerobic oxidation of primary sulfones to carboxylic acids
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Primary alkyl aryl sulfones are converted to the corresponding carboxylic acids in fair to excellent yield through double deprotonation and exposure to atmospheric oxygen. The methodology allows for the convenient synthesis of 13C labeled carboxylic acids.
- Bonaparte, Amy C.,Betush, Matthew P.,Panseri, Bettina M.,Mastarone, Daniel J.,Murphy, Ryan K.,Murphree, S. Shaun
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supporting information; experimental part
p. 1447 - 1449
(2011/05/08)
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- Structure and reactivity in the hydrolyses of aliphatic carboxylic acid esters and chlorides
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For hexanoic acid and its seven isomers, relative rates have been determined for acid catalysed esterification with methanol, and compared with those for saponification of the methyl esters. A good correlation between logarithms of relative rates for the two reactions is obtained, and it is suggested that the eight isomers provide a test set of compounds in which steric effects alone act on reactivity at the acyl carbon. A full set of steric parameters (Es′ values) are presented. Rates of solvolyses of the acid chlorides- of the isomers have been determined conductometrically in 3:1 wt:wt acetonitrile water. Logarithms of relative rates show a poor correlation with Es′, and, taking into account the solvent dependence of the rates, the pattern excludes both rate-limiting formation of a tetrahedral intermediate and rate-limiting dissociation of chloride to form acylium ions. The remaining possibilities, a concerted process (ANDN?) and rapid reversible formation of a hydrate followed by rate-limiting dissociation of chloride (AN + DN?,) are considered. Copyright
- Regan, Andrew C.,Watt, C. Ian F.
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p. 180 - 189
(2008/02/06)
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- Process for the preparation of carboxylic acids and derivatives of them
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The subject matter of the invention is a process for the preparation of carboxylic acids and derivatives of them of the general formula STR1 wherein R means hydrogen, or a C1-4 alkyl or a (C1-5 alkoxy)carbonyl group, R1 is as defined in claim 1, R7 stands for hydrogen or a C1-7 alkyl group and R8 means hydrogen or a carboxyl group, by reacting a 1,3-dioxane-4,6-dione derivative of the general formula STR2 wherein R9 stands for a C1-4 alkyl group or a phenyl group, optionally monosubstituted by halogen and R10 stands for hydrogen or a C1-5 alkyl group or R9 and R10 together form a pentamethylene group, and an aldehyde or ketone of the general formula STR3 in the presence of formic acid.
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- Processes for producing aromatic polycarbonate oligomer and aromatic polycarbonate
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A process for producing continuously an aromatic polycarbonate oligomer by reacting an aromatic dihydroxy compound and an alkali metal base or an alkaline earth metal base with a carbonyl halide compound comprises: (1) feeding continuously to a tank reactor an aromatic dihydroxy compound, water, a molecular weight controlling agent, a polymerization catalyst, a carbonyl halide compound, and an organic solvent, and an alkali metal base or an alkaline earth metal base in an amount of 1.15-1.6 equivalents based on the aromatic dihydroxy compound, (2) carrying out the reaction with a residence time as defined by the following formula, where X is an amount of the polymerization catalyst in terms of mole % based on the amount of mole of the aromatic dihydroxy compound fed per unit time, and Y is a residence time (min.), and (3) continuously withdrawing the reaction mixture from the tank reactor to obtain an aromatic polycarbonate oligomer having a number average molecular weight of 1,000-10,000. An aromatic polycarbonate is produced by polycondensation of the aromatic polycarbonate oligomer.
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- Process for the preparation of carboxylic acids and derivatives of them
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The subject matter of the invention is a process for the preparation of carboxylic acids and derivatives of them of the general formula wherein Rmeans hydrogen, or a C1 4alkyl or a (C1 5alkoxy)carbonyl group, R1is as defined in claim 1, R7stands for hydrogen or a C1 7alkyl group and R8means hydrogen or a carboxyl group, by reacting a 1,3-dioxane-4,6-dione derivative of the general formula wherein R9stands for a C1 4alkyl group or a phenyl group, optionally monosubstituted by halogen and R10stands for hydrogen or a C1 5alkyl group or R9 and R10together form a pentamethylene group, and an aldehyde or ketone of the general formula in the presence of formic acid and of [a] amine(s) and, if desired, of an alcohol of the general formula, , R7 - OH VI,, , wherein R7is a C1 7alkyl group, at a temperature of 20 to 140°C, and/or, reducing an unsaturated 1,3-dioxane-4,6-dione derivative of the general formula and/or, a 1,3-dioxane-4,6-dione derivative of the general formula with formic acid in the presence of [a] amine(s) and, if desired, of an alcohol as above defined.
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- HETEROCUMULENES IN ACYLATION REACTIONS II. REACTIVITY OF ALKYL-SUBSTITUTED KETENES IN SPONTANEOUS HYDROLYSIS REACTIONS
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The structures and electronic states of six ketenes were investigated by the semiempirical MNDO, MINDO/3, and AM1 quantum-chemical methods.The kinetics of the spontaneous hydrolysis of mono- and dialkylsubstituted ketenes in water and water-acetonitrile mixtures at 20 deg C were studied.The induction and steric effects of the substituents on the process rate were evaluated quantitatively in terms of a ρ? analysis.An increase in the number, length, and branching of the hydrocarbon substituents at the terminal carbon atom of the ketenes leads to a large decrease in the hydrolysis rate.The results of the calculations were compared with experimental data.Possible alternatives for the mechanism of the process are discussed.
- Lyashchuk, S. N.,Skrypnik, Yu. G.
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- Multiple behaviors in the cleavage of aryl alkanoates by αand β-cyclodextrins. Processes involving two molecules of cyclodextrin
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The kinetics of ester cleavage of 4-carboxy-2- nitrophenyl alkanoates (1) (C2-C8) and of 2- carboxy-4-nitrophenyl alkanoates (2) (C2, C4,C6, C8) in an aqueous phosphate buffer (pH 11.7) containing α- orβ-cyclodextrin (α- or β-CD) show various types of behavior. Depending on the ester, its acyl chain, and the CD, the kinetics show acceleration (with or without saturation), retardation, acceleration and retardation, retardation and acceleration, or two kinds of acceleration. However, this diversity can be rationalized with simple reaction schemes. Short-chain esters mainly react conventionally through binary CD-ester complexes. For longer chains, some ester/CD combinations exhibit nonproductive 2:1 (CD:ester) binding, whereas other combinations show a cleavage process involving two CD molecules. The latter is most likely due to the attack of a CD (anion) on the 1:1 CD-ester complex or to reaction within a weak 2:1 complex. Modes of transition-state binding are probed using the pseudoequilibrium constants (KTS) introduced in earlier work (Carbohydr. Res. 1989, 192, 181).
- Tee, Oswald S.,Du, Xian-Xian
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p. 620 - 627
(2007/10/02)
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- Organoboranes for Synthesis. 14. Convenient Procedures for the Direct Oxidation of Organoboranes from Terminal Alkenes to Carboxylic Acids
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For the first time, a highly efficient and direct oxidation of a variety of organoborane intermediates into carboxylic acids has been demonstrated, without an increase or decrease of carbon atoms.Synthetically useful procedures have been developed for the ready conversion of representative terminal alkenes into carboxylic acids via oxidation of the organoboranes obtained by hydroboration of the terminal alkenes.The oxidation works well with a variety of organoboranes derived from reagents such as dibromoborane-methyl sulfide (HBBr2*SMe2), monobromoborane-methyl sulfide (H2BBr*SMe2), monochloroboran-methyl sulfide (H2BCl*SMe2), borane-methyl sulfide (H3B*SMe2), thexylborane (H2BThx), and dicyclohexylborane (HBChx2).The oxidation is achieved in a convenient manner with pyridinium dichromate (PDC), sodium dichromate in aqueous sulfuric acid (Na2Cr2O7-H2SO4) and chromium trioxide in 90 percent aqueous acetic acid (CrO3-HOAc-H2O).These oxidations afford carboxylic acids in very good yields with complete retention of the structure of the organic group attached to boron.
- Brown, Herbert C.,Kulkarni, Shekhar V.,Khanna, Vijay V.,Patil, Virendra D.,Racherla, Uday S.
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p. 6173 - 6177
(2007/10/02)
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- Selective Oxidation of Alcohols and Aldehydes with Hydrogen Peroxide Catalyzed by Methyltrioctylammonium Tetrakis(oxodiperoxotungsto)phosphate(3-) under Two-Phase Conditions
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The use of methyltrioctylammonium tetrakis(oxodiperoxotungsto)phosphate(3-) (1c) in combination with hydrogen peroxide as the primary oxidant in an aqueous/organic biphase system provides a cheap, efficient, and versatile catalytic method for alcohol and aldehyde oxidation.By this method, a variety of water-insoluble primary and secondary alcohols and aldehydes were oxidized to carboxylic acids and ketones in good yields under mild conditions and after relatively short reaction times.
- Venturello, Carlo,Gambaro, Mario
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p. 5924 - 5931
(2007/10/02)
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- Phosphoramidate peptide inhibitors of human skin fibroblast collagenase
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An extensive series of N-(monoethylphosphoryl)peptides was synthesized and their inhibition of purified human skin fibroblast collagenase examined. At the cleavage site S1 all reported compounds have the (EtO)(OK)P(O) group and the peptide side chain extended toward the C-terminal end (up to P5') of the substrate sequence. These phosphoramidates with a tetrahedrally hybridized phosphorus atom are thought to be transition state analogue inhibitors. They exhibited fair inhibitory potency against this vertebrate collagenase having K(i) values in the micromolar range. The most potent of these, (EtO)(OK)P(O)-Ile-TrpNHCH3 (68), inhibits with a K(i) value of 1.5 μM and is nearly 100 times stronger than (EtO)(OK)P(O)-Ile-Ala-GlyOK (51) (K(i) of 140 μM), which has the sequence matching that of the α1(I) chain of collagen in P1', P2', P3' after the cleavage site. Several compounds were prepared in an attempt to identify the nature of the S2', S3', and S4' binding sites. Alanine at the P2' position was replaced by leucine, phenylalanine, tryptophan, or tyrosine derivatives, resulting in K(i) values in a significantly lower range, 1.0-40 μM, compared to 51. No upper size limitation or specificity has been found at this position, yet similar replacements at the P3' position, which is occupied naturally by a glycine residue, gave weaker inhibitors: (EtO)(OK)P(O)-Ile-Tyr(OBzl)-PheOK (57) had a K(i) of 120 μM. Hexapeptide derivatives had weaker activities in the 270 μM-2 mM range. All inhibitors were evaluated by using the synthetic thio peptolide spectrophotometric assay.
- Kortylewicz,Galardy
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p. 263 - 273
(2007/10/02)
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- Direct Synthesis of Carboxylic Acids from Organoboranes
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Direct Synthesis of carboxylic acids through a two carbon atom homologation from organoboranes has been achieved, by the reaction with the dianion of phenoxyacetic acid.It is now possible to synthesize alkanoic, alkenoic, or alkynoic acids, from the corresponding alkenes, dienes, or enynes, respectively, via hydroboration.The reaction is tolerant of various functional groups present in alkenes, thus giving the corresponding carboxylic acids with chloro, sulfide, ether, acetal, and thioacetal functionalities in good yields.
- Hara, Shoji,Kishimura, Kotaro,Suzuki, Akira,Dhillon, Ranjit S.
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p. 6356 - 6360
(2007/10/02)
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- LITHIATED CYCLOPROPANONE KETALS
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The ketene acetal I reacted with dibromocarbene yielding the dibromocyclopropanone ketal II, which was reduced to the monobromide III by treatment with tri-n-butyltin hydride.Reaction of III with n-butyllithium at -78 degC yielded the lithiated cyclopropanone ketal IV, which yielded adducts with acetone, cyclohexanone, cyclohexenone, 3,3,3-trimethoxybutan-2-one, and 3-pentanone.
- Dowd, Paul,Kaufman, Christopher,Kaufman, Paul,Paik, Yi Hyon
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p. 2279 - 2282
(2007/10/02)
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- An Oxidative Ether Cleavage with p-Nitroperbenzoic Acid
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The reaction of p-nitroperbenzoic acid in chloroform with alkyl ethers (1a, 2a) leads by selective attack at C - H bonds in α-position to the ether oxygen to hemiacetals, which decompose to aldehydes and alcohols, yielding carboxylic acids.Secondary alkoxy groups as in 3a, 4a furnish Baeyer-Villiger oxidation products of initially formed ketones. Kinetic measurements with substituted benzyl methyl ethers show a Hammett reaction constant ρ = -0.9, which is in accordance with the observed relatively small discrimination between secondary and tertiary C - H bonds.The results are compared with similar hydroxylations of alkanes and with monooxygenase reactions and point to oxenoid transition states.Radical reactions as found with some alkanes are not observed, which is shown by the small amounts of nitrobenzene ( 10percent) formed during the reaction. 13C-NMR shifts of several ethers and oxidation products are reported.
- Schneider, Hans-Joerg,Ahlhelm, Alfred,Mueller, Walter
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p. 3297 - 3302
(2007/10/02)
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- Organoboranes. 35. Reaction of Alkylthioboronic Esters with Trichloromethyllithium: Preparation of One-Carbon-Extended Carboxylic Acids and Thioacetals from Alkenes via Hydroboration
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Various 2-alkyl-1,3,2-dithiaborolanes, RB(S2C2H4) (1), were converted to the corresponding carboxylic acids, RCO2H (2), by using LiCCl3 in THF, followed by oxidation with alkaline hydrogen peroxide.For R=hexyl, a reaction intermediate is converted by solvent into another compound, C6H13C(S2C2H4)B2 (9a), characterized spectroscopically.The yields of 2 decreased with increasing bulkiness of the alkyl groups R.Although the configuration of R= trans-2-methylcyclopent-1-yl (1k) was retained in the product (>98percent trans), a significant degree of epimerization tookplace for R= exo-norbornyl (1j) during the oxidation (exo : endo = 86 : 14).More uniquely, the intermediates 9 were easily hydrolyzed by heating the reaction mixture with aqueous NaOH to give the corresponding 2-alkyl-1,3-dithiolanes 3.Stereochemical integrity was retained in the products derived from 1j and 1k.Since 1 was prepared by the hydroboration of alkenes, this sequence provides a new method for introducing oxycarbonyl or thioacetal functionality into alkenes in a regioselective manner, and, in the case of 3, also with stereocontrol.
- Brown, Herbert C.,Imai, Toshiro
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p. 892 - 898
(2007/10/02)
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- N-Substituted mercaptoacyl pripionamides
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Mammalian collagenase is inhibited by compounds having the formula STR1 or a salt thereof, wherein R1 is hydrogen, alkanoyl of 2 to 10 carbon atoms, or arylcarbonyl; STR2 wherein R4 is hydrogen, alkyl or aryl; R3 is alkyl of 3 to 8 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, aryl or arylalkyl; and n is an integer of 1 to 20.
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- Piperazinone and piperazine polypeptides
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Piperazinone polypeptides which are useful as analgesics and psychotherapeutic agents as well as processes to produce them are described.
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- Synthesis Gas Homologation of Aliphatic Carboxylic Acids
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A new preparative route to aliphatic carboxylic acids is described involving a novel homologation using synthesis gas catalysed by soluble ruthenium species coupled with iodide promotors.
- Knifton, John F.
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- COPPER-CATALYZED REACTION OF GRIGNARD REAGENTS WITH β-PROPIOLACTONES: A CONVENIENT METHOD FOR THE SYNTHESIS OF Β-SUBSTITUTED PROPIONIC ACIDS
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Grignard reagents react with β-propiolactones in the presence of a copper(I) catalyst to give β-substituted propionic acids in high yields.
- Sato, Toshio,Kawara, Tatsuo,Kawashima, Masatoshi,Fujisawa, Tamotsu
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p. 571 - 574
(2007/10/02)
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- Action d'organolithiens et organomagnesiens sur la propiolactone en presence de sel cuivreux Synthese d'acides carboxyliques
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Organocuprate reagents, as well as Grignard reagents under the catalytic action of copper bromide, react with propiolactone to give the corresponding homologous acid with three more carbon atoms in good yields.
- Normant, J. F.,Alexakis, A.,Cahiez, G.
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p. 935 - 938
(2007/10/02)
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- Inhibitors of mammalian collagenase
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Mammalian collagenase is inhibited by compounds having the formula STR1 and salts thereof, wherein R 1 is hydrogen or alkanoyl of 2 to 10 carbon atoms;R 2 is hydroxy, amino, or STR2 R 3 is hydrogen, alkyl of 1 to 4 carbon atoms, STR3 R 4 is hydroxy, amino, arginine, leucine, glutamine, alanine or glycine; andm is 0 or an integer of 1 to 9.
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- Reduction of Isopropylidene Acylmalonates, 5-Acylbarbituric Acids, and 3-Acyl-4-hydroxycoumarins to the Corresponding Alkyl Derivatives by Sodium Cyanoborohydride-Acetic Acid
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Isopropylidene acylmalonates, 5-acylbarbituric acids, and 3-acyl-4-hydroxycoumarins are readily reduced to the corresponding alkyl derivatives by sodium cyanoborohydride-acetic acid.The cyclic substrates are readily prepared by the acylation of isopropylidene malonate, barbituric acid (or its N,N'-dimethyl derivative), and 4-hydroxycoumarin, according to procedures developed by other workers.The reductions take place upon addition of a 2 mol equiv of sodium cyanoborohydride to a mixture of the acyl compound and acetic acid.This reductive transformation completes a synthetic method for the preparation of the alkyl derivatives starting from the parent compound.
- Nutaitis, Charles F.,Schultz, Rose Ann,Obaza, Judy,Smith, Francis X.
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p. 4606 - 4608
(2007/10/02)
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- A THREE CARBON HOMOLOGATION BY THE RING-OPENING OF β-PROPIOLACTONES WITH DIORGANOCUPRATES
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Various organocuprates react with β-propiolactones to give β-substituted propionic acids in high yields.
- Fujisawa, Tamotsu,Sato, Toshio,Kawara, Tatsuo,Kawashima, Masatoshi
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p. 2181 - 2184
(2007/10/02)
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