Malonate Addition Research Articles

Synthesis of novel pyropheophorbide a-fullerene conjugates

Two pyropheophorbide a units were attached via a malonate addition reaction to the [60]fullerene core to give a trichromophoric system. Also, in a different approach two pyropheophorbide a moieties were coupled to a hexasubstituted [60]fullerene diol. The mono-adduct was very light and oxygen sensitive whereas the corresponding hexaadduct showed a much higher stability.

Stereospecific Pd(O)‐Catalyzed Malonate Additions to Allylic Hydroxy Phosphonate Derivatives: A Formal Synthesis of (‐)‐Enterolactone.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Stereospecific Pd(O)-catalyzed malonate additions to allylic hydroxy phosphonate derivatives: a formal synthesis of (-)-enterolactone.

A combination of cross-metathesis and malonate addition was applied to a formal synthesis of the mammalian lignan enterolactone 5. The cross-metathesis of alkene 6 and phosphonate 3a gave the substituted allylic phosphonate 3d. The palladium-catalyzed addition of malonate 10d to the allylic phosphonate 3d was stereospecific and highly regioselective and yielded the vinyl phosphonate 11d. The vinyl phosphonate 11d was converted in two steps into the lactone 14, a known intermediate in the synthesis of enterolactone 5.

Regioselectivity in the Palladium-Catalyzed Addition of Carbon Nucleophiles to Dihydropyran Derivatives

The regioselectivity of Pd-catalyzed malonate or sulfonylacetate addition to dihydropyran derivatives is highly dependent upon the substitution pattern of the dihydropyran nucleus and is governed by electronic, rather than steric factors. In certain instances, subtle steric features also play a role in controlling regioselectivity by altering the conformation of the intermediate η3-allyl Pd-complex.

Malonate decarboxylase of Klebsiella pneumoniae catalyses the turnover of acetyl and malonyl thioester residues on a coenzyme-A-like prosthetic group.

During aerobic growth of Klebsiella pneumoniae on malonate, a soluble malonate decarboxylase is induced. Malonate decarboxylation consumes a proton (not H2O) and forms acetate and CO2 (not HCO3-) as products. The enzyme was purified 56-fold to apparent homogeneity. It has a native molecular mass of 142 kDa and consists of four subunits alpha, beta, gamma and delta with molecular masses of 65, 34, 30, and 12 kDa, respectively. Two different forms of the enzyme were recognised: a catalytically inactive SH-enzyme and the catalytically active acetyl-S-enzyme which is formed by post-translational acetylation of the SH-enzyme with ATP, acetate and a specific ligase. The acetyl-S-enzyme was converted into the SH-enzyme by incubation with hydroxylamine or dithioerythritol. Chemical reacylation of the SH-enzyme, which restores catalytic activity, was achieved with acetic anhydride or more efficiently with malonyl-CoA. This acylation of the SH group was prevented after incubation with various thiol-specific reagents. After incubation of the SH-enzyme with iodo[1-14C]acetate, the delta subunit became specifically labelled. This subunit was also labelled after incubation of the acetyl-S-enzyme with [2-14C]malonate. The radioactivity was completely liberated from the protein upon malonate addition. These results indicate that the delta subunit is the acyl-carrier protein of the complex and that malonate decarboxylation proceeds in two steps: the acetyl residue on the ACP is first replaced by a malonyl residue which subsequently undergoes decarboxylation thereby regenerating the acetyl-S-ACP. The binding site for the acyl residues on the acyl-carrier protein was shown to be 2'-(5"-phosphoribosyl)-3'-dephospho-CoA after alkaline cleavage of this prosthetic group from the enzyme and chromatographic as well as mass spectroscopic analyses.

On the Stereoselectivity of the (-)-Dimenthyl Malonate Addition to α,β-Unsaturated Ketones

The Michael addition of (-)-dimenthyl malonate to eight α,β-unsaturated ketones has been studied. The ratio of diastereomers was calculated on the basis of the 1H NMR spectra of the crude reaction products. The diastereomer excess varied from 10 to 50%, depending on the structure of the starting enone. The pure diastereomer produced by addition of (-)-dimenthyl malonate to 2-benzylidene-1,4-indandione was isolated by repeated crystallization. X-ray analysis has shown that the isomer is (-)-dimenthyl (R)-2-[1-(1,3-dioxoindan-2-yl)-1-phenylmethyl]malonate (5a). The predominating diastereomers of (-)-dimenthyl(3-ferrocenyl-3-oxophenylpropyl)malonate (1a) and (-)-dimenthyl-2-(1-(1,3-dioxo[3]ferrocenophan-2-yl)-1-phenyl malonate (6a) were also isolated in pure state by careful crystallization.

Synthesis of 2,4-Dihydropyrrolo[3,4-b]pyrroles and 4,6-Dihydro-2H-dipyrrolo[3,4-b:3',4'-d]pyrroles

The title labile heterocyclic ring systems were prepared by the phosphineimine-alkylidenemalonate cyclisation reaction or the retro- malonate addition reaction. An X-ray structure analysis confirmed that three pyrrole rings of 4,6-dihydro-2H-dipyrrolo [3,4-b:3',4'-d]pyrroles are coplanar.

PENTHIAZOLINES. I. THE ACTION OF HALOGENS ON THE DIMETHYL MALONATE ADDITION PRODUCT OF ALLYL MUSTARD OIL1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPENTHIAZOLINES. I. THE ACTION OF HALOGENS ON THE DIMETHYL MALONATE ADDITION PRODUCT OF ALLYL MUSTARD OIL1David E. WorrallCite this: J. Am. Chem. Soc. 1932, 54, 5, 2061–2066Publication Date (Print):May 1, 1932Publication History Published online1 May 2002Published inissue 1 May 1932https://doi.org/10.1021/ja01344a057RIGHTS & PERMISSIONSArticle Views37Altmetric-Citations5LEARN 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 (391 KB) Get e-Alerts Get e-Alerts