Homologation Of Esters Research Articles

Additions and Corrections - Boronic Ester Homologation with 99% Chiral Selectivity and Its Use in Syntheses of the Insect Pheromones (3S, 4S)-4-Methyl-3-heptanol and exo-Brevicomin

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdditions and Corrections - Boronic Ester Homologation with 99% Chiral Selectivity and Its Use in Syntheses of the Insect Pheromones (3S, 4S)-4-Methyl-3-heptanol and exo-BrevicominDonald Matteson and Kizhakethil SadhuCite this: J. Am. Chem. Soc. 1983, 105, 19, 6195Publication Date (Print):September 1, 1983Publication History Published online26 April 2004Published inissue 1 September 1983https://doi.org/10.1021/ja00357a602RIGHTS & PERMISSIONSArticle Views54Altmetric-Citations-LEARN 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 (147 KB) Get e-Alerts Get e-Alerts

Homologation of carboxylic methyl esters via reductive carbonylation catalyzed by a cobalt-ruthenium mixed catalyst

Abstract Mixtures of cobalt acetate and ruthenium acetylacetonate promote the homologation of carboxylic methyl esters to the corresponding ethyl esters by CO-H 2 . The reaction of methyl formate is considered separately because of its tendency to decarboxylate. The behavior of five other methyl esters is considered as a function of the length and the size of the acyl group. In each case reductive carbonylation of the methyl ester gives methanol, ethanol, the carboxylic acid, and the ethyl ester. The formation of the last product is enhanced by the mixture of Co and Ru complexes. The mechanism is thought to be essentially the same as that previously proposed for homologation of methyl acetate.

Boronic ester homologation with 99% chiral selectivity and its use in syntheses of the insect pheromones (3S,4S)-4-methyl-3-heptanol and exo-brevicomin

Boronic ester homologation with 99% chiral selectivity and its use in syntheses of the insect pheromones (3S,4S)-4-methyl-3-heptanol and exo-brevicomin

.alpha.-Trimethylsilyl boronic esters. Pinacol lithio(trimethylsilyl)methaneboronate, homologation of boronic esters with [chloro(trimethylsilyl)methyl]lithium, and comparisons with some phosphorus and sulfur analogs

.alpha.-Trimethylsilyl boronic esters. Pinacol lithio(trimethylsilyl)methaneboronate, homologation of boronic esters with [chloro(trimethylsilyl)methyl]lithium, and comparisons with some phosphorus and sulfur analogs

Homologation of Methyl Esters Catalyzed by Ruthenium–Cobalt Bimetallic Systems

Abstract Reactions of methyl esters such as methyl acetate with synthesis gas have been investigated by use of the mixed clusters such as [Et4N][RuCo3(CO)12] and [Et4N][Ru3Co(CO)13] or a combination of Ru(acac)3 and Co2(CO)8 as catalyst and methyl iodide as promoter. In the homologation of methyl acetate, the catalytic activity for formation of ethyl acetate was much improved when both ruthenium and cobalt existed in the reaction system.

High-performance liquid chromatography of eburnane alkaloids : I. Separation on reversed phases

Separation of eburnane alkaloids using reversed-phase high-performance liquid chromatography was investigated on μBondapak C 18 and LiChrosorb RP-8 columns with acetonitrile—aqueous 0.01 M ammonium carbonate as eluent. The method can be successfully applied for the group separation of eburnane alkaloids as well as for the separation of stereoisomers and of ester homologues.

Separation of vinca alkaloids by GLC

A new GLC method was developed for the separation of vinca alkaloids. OV-101 stationary phase and programmed temperature analysis were used for the investigations. By this method the separation of closely related vinca alkaloids can be performed such as stereo and structural isomers, ester homologues of vincaminic and apovincaminic acids.

Homologation of boronic esters with trimethylsilylchloromethyllithium

Trimethylsilylchloromethyllithium adds to boronic esters to form ate complexes which rearrange with displacement of chloride to form the homologous α-trimethylsilyl boronic esters in high yields.

Stimulation of 86Rb+ and 32Pi movements in 3T3 cells by prostaglandins and phorbol esters.

The potent tumor promoter tetradecanoyl phorbol acetate (TPA) induces early changes in ion movements analogous to those induced by prostaglandins E1 and F 2alpha. Among the earliest changes induced by TPA is a significant increase in 32Pi incorporation within 15 minutes incubation of TPA (10(-8)-10(-6) M) with post-confluent Swiss 3T3 mouse embryonic fibroblasts. Similarly, the active phorbol ester homolog 4-beta-OH phorbol didecanoate but not the inactive stereoisomeric 4-alpha-OH phorbol didecanoate stimulated 32Pi incorporation. Also, TPA at the above concentrations stimulated 86Rb+ influx shortly after administration. Both fluxes were ouabain-sensitive in accord with the idea that an early effect of TPA is to alter (Na+ + K+)-ATPase activity. Further, prostaglandin E1 (10(-7)-10(-6) M) and prostaglandin F 2alpha (3 X 10(-9)-10(-7) M) caused a similar stimulation of 86Rb+ and 32Pi uptake. The finding that water-soluble prostaglandin F 2alpha also exhibited stimulatory effects indicated that those hormone-induced responses are not mediated by solvent interactions. The similar responses of phorbol esters and prostaglandin derivatives suggests that phorbol esters and prostaglandin derivatives may act at common membrane sites. The finding that stimulatory effects were observed at discrete times in the logarithmic phase of growth suggests that the activation of membrane receptors may be cell-cycle dependent.

Pharmacokinetics of methylphenidate in the rat using single-ion monitoring GLC-mass spectrometry.

A GLC-mass spectrometric assay for methylphenidate in biological fluids was developed using the ethyl ester homolog of the drug as the internal standard. The procedure has a lower level of sensitivity of 1.2 ng/ml and is based on GLC-mass spectrometic monitoring of the m/e 180 ion common to the mass spectra of the N-trifluoroacetyl derivatives of the drug and internal standard. The brain and plasma levels of methylphenidate in rats were determined after intravenous administration of 0.5 mg/kg of the drug. The two-compartment open pharmacokinetic model fit the data.

Jojoba oil analysis by high pressure liquid chromatography and gas chromatography/mass spectrometry

AbstractTwo analytical procedures for determining com‐positions of jojoba liquid wax esters are described and compared. One, the more tedious, involves separation of wax ester homologs by high pressure liquid chro‐matography followed by determination of the acid and alcohol moieties from each homolog. The second allows rapid determination of wax ester composition by gas Chromatographic separation of hydrogenated jojoba wax esters according to chain length, followed immediately by ancillary mass spectrometric identifi‐cation of the acid and alcohol moieties. Double bonds in the alkyl chains in jojoba liquid waxes were almost exclusively (98%) ω‐9, when examined by gas chro‐matography/mass spectrometry (GC/MS) and ozonolysis/GC/MS.

The Reaction of Ethyl Ethoxymethylenecyanoacetate with Its Hydrazino Derivatives

Abstract The reaction of ethyl ethoxymethylenecyanoacetate with its hydrazino derivative in the presence of pyridine in ethanol at room temperature gave ethyl (4-ethoxycarbonyl-5-aminopyrazol-1-yl)methylenecyanoacetate(6) and two geometric isomers of ethyl (4-ethoxycarbonylpyrazol-5-ylamino)methylenecyanoacetate(7). Compound 6 itself, under the same conditions, rearranged to compound 7. Both compounds, 6 and 7, upon heating cyclized exclusively to the same product, diethyl 7-aminopyrazolo[1,5-a]pyrimidine-3,6-dicarboxylate(8). From the results of other combination reactions on methylenecyanoacetic ester homologs, a plausible reaction mechanism involving a rearrangement is discussed.

Microspectrophotometry of macrophage lysosomal enzyme activity: A measure of polymer implant tissue toxicity

Samples of polyvinyl chloride (PVC) plasticized with 7 phthalate ester homologs, PVC with dibutyl tin, polypropylene, and USP polyethylene control, were prepared as 1-mm diameter rods and implanted into rat gluteal muscle for 7, 10, and 14 days. A sham control was included. Cryostat sections of the implant sites were prepared and tested for acid phosphatase activity by a dye coupling procedure. A Zeiss microspectrophotometer unit was employed at 530 nm for measuring the total activity at the 7- and 14-day implant sites, and for measuring activity in a 30-μ diameter area in the tissue reaction zone at 10 days. PVC with di-n-amyl-phthalate and PVC with dibutyl tin samples were associated with a higher lysosomal enzyme (acid phosphatase) response than the other samples examined. The USP and polypropylene samples elicited the lowest enzyme response. It was concluded that the measurement of lysosomal enzyme activity by microspectrophotometry in evaluating implant tissue toxicity has definite advantages. Foremost, it relieves the investigator from relying solely on microscopic and visual subjective observations in judging histocompatibility and tissue toxicity.

Plant Growth Inhibition and Membrane Penetration by a Homologous Series of Dichlorobenzoate Esters

AbstractThe homologous series of n‐alkyl esters (C1–C10) of 3,4‐dichlorobenzoic acid was synthesized and their effects in inhibiting the growth of Nicotiana meristems were studied. The inhibition of growth was considered in terms of penetration of chemicals into the plant tissue and subsequent cell membrane disruption. Penetration was investigated by applying the emulsified ester to the meristem and then measuring the compound recovered with the isolated surface lipids. Decreasing amounts of 3,4‐dichlorobenzoate esters penetrated into the plant as the alkyl chain length of the ester moeity was increased. Essentially no penetration occurred with the n‐C7 through C10 esters tested. The effect of the ester homologues on cell membranes was studied by measuring the efflux of betacyanin from beet root cells. Decreasing amounts of pigments were released as the alkyl chain length of the ester was increased. Minimal cell membrane disruption was found for the C7–C10 esters. Inhibition of the plant meristem may result from the more rapid penetration of the short chain ester homologues into the plant.

The composition of beeswax alkyl esters

AbstractThe alkyl esters of beeswax, after isolation from the unhydrolyzed wax by preparative layer chromatography (PLC), have been analyzed directly by high temperature GLC using 1.5% OV1 as liquid phase. In two commercial wax samples examined the ester homologues are predominantly even carbon numbered ranging from C36 to C54. The principal alkyl esters are C40, C42, C44, C46 and C48. The GLC analysis of the ester hydrolysis products revealed that the variations in ester chain length are produced by variations in the esterified primary alcohol chain lengths. The esterified fatty acid is chiefly hexadecanoic acid. The esterified fatty acids differ in composition from the free fatty acids which are also present in the wax.