Keto Diesters Research Articles

Novel domino procedures for the synthesis of chromene derivatives and their isomerization.

Novel tricyclic keto diesters have been synthesized by a one-pot three-component procedure via DABCO-catalyzed domino Knoevenagel-Michael addition reactions. Also, an efficient four-component reaction for the synthesis of another new group of tricyclic keto diesters has been developed via domino Knoevenagel-intramolecular oxo-Diels-Alder reactions. A selective thermal isomerization of the synthesized chromenes to fumarates is also described. X-ray analyses confirm unambiguously the structures of the products.

Molecular structures and preferred conformations of stabilized keto diester phosphonium ylides

Triphenylphosphonium ylidic keto diesters with a nonylidic ester group, Ph 3P C(CO 2CH 2CH 3)CO CO 2CH 2CH 3, 1, and Ph 3P C(CO 2CH 2CH 3)CO CH 2 CO 2CH 2CH 3, 2, have the keto group syn and the ylidic ester acyl group anti to phosphorus. Conformation of 2 is assigned by X-ray crystallography, while conformations of 1 and 2 are based on 1H and 13C NMR spectroscopy, and comparisons of acyl stretching frequencies with predicted values from HF and DFT methods. Thermolyses of 1 and 2 gave the expected acetylene derivatives in high yield, consistent with the syn keto conformation and in agreement with earlier observations of thermolyses of stabilized phosphonium ylides. Results from the X-ray spectrum of 2 confirm the proposed structure.

Conformations of diester triphenylphosphonium ylides with an ylidic ester or keto and ester ylidic groups

The structures of three related keto diester and diester ylides, namely diethyl 3-oxo-2-(triphenylphosphoranylidene)glutarate, C(27)H(27)O(5)P, (I), diethyl 3-oxo-2-(triphenylphosphoranylidene)glutarate acetic acid monosolvate, C(27)H(27)O(5)P·C(2)H(4)O(2), (II), and diethyl 2-(triphenylphosphoranylidene)succinate, C(26)H(27)O(4)P, (III), are presented. The syn-keto anti-ester conformations in the crystalline keto diesters are governed by electronic delocalization between the P-C and ylidic bonds and an acyl group, and by intra- and intermolecular interactions. There are also intramolecular attractive and repulsive interactions of different types (C-H...O and C-H...π) controlling the molecular conformations. The mono-ylidic diester (III) has an anti-ester conformation, while those for (I) and (II) are related to pyrolytic formation of acetylene derivatives. The terminal nonylidic ester group in (I) was disordered over two sets of almost equally populated positions.

ChemInform Abstract: Samarium(II) Iodide Induced Cascade Reaction for Tricyclic γ‐Lactone Synthesis from Acyclic Keto Diesters.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Samarium(II) iodide-induced cascade reaction for tricyclic γ-lactone synthesis from acyclic keto diesters

Cascade reaction involving reductive cyclization, Dieckmann condensation, and lactonization of E- and Z-dimethyl 2-methyl-8-oxoundec-2-enedioates and Z-dimethyl 2-methyl-7-oxodec-2-enedioate with samarium(II) iodide was found to stereospecifically produce cis and trans bicyclo[4.4.0]decane (decalin) ring systems and trans bicyclo[4.3.0]nonan (perhydroindane) ring system each consisting of γ-lactone, respectively.

Solid-Phase Synthesis of Pyrazoledicarboxylic Acid Derivatives

The solid-phase synthesis of a small library of 1,5-disubstituted pyrazole-3,4-dicarboxylic acid derivatives is described. A mono amide of oxalic acid 1 was anchored onto Wang resin to give 2 (Step I). The amide functional group of intermediate 2 was then dehydrated to afford resin-bound cyanoformate 3 (Step II). Subsequent functionalization of 3 was accomplished using an excess of dicarbonyl compounds in the presence of zinc acetylacetonate to give 4a-d (Step III). The solid-supported enamino keto diesters 4a-d reacted with hydrazines (Step IV) to give pyrazoles 5a-n from which the pyrazoledicarboxylic acid derivatives 6a-n were readily released via acidic cleavage (Step V).

The asymmetric Michael-type alkylation of chiral β-enamino esters: critical role of a benzyl ester group in the racemization of adducts

In contrast with keto diester ( R)- 10a bearing a methyl ester group at the quaternary carbon center, the benzyl ester analogue ( R)- 10a partially racemized during workup, thereby revealing that the nature of the ester group at the quaternary carbon center has a critical role in the rate of racemization of such Michael adducts.

Expeditious Solid‐Phase Synthesis of Pyrazoledicarboxylic Acid Derivatives by Functionalization of Resin‐Bound Cyanoformate

AbstractEsterification of the Wang resin 5 with the monoamide of oxalic acid (oxamic acid, 7) followed by dehydration of the amide function furnishes the resin‐bound cyanoformate 9, which can be elaborated by zinc‐catalyzed reaction with β‐keto esters. The obtained enamino keto diesters 10a–d react with hydrazines affording, after removal from the solid support, fully substituted pyrazoledicarboxylic acids 12a–n. Optimization of the above sequence and the solid‐phase synthesis of a small test‐library of 1,5‐disubstituted pyrazole‐3,4‐dicarboxylic acid derivatives are described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Michael Addition of Nitroalkanes to Dimethyl Citraconate, with DBU as Base: An Unexpected, One‐Pot Synthesis of Polyfunctionalized Carbonyl Derivatives.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Michael Addition of Nitroalkanes to Dimethyl Citraconate, with DBU as Base: An Unexpected, One-Pot Synthesis of Polyfunctionalized Carbonyl Derivatives

Michael addition of nitroalkanes to dimethyl citraconate, with DBU as base, allows the one pot formation of keto diesters. The reaction proceeds through an equilibrium form of the acceptor, followed by Michael addition ofthe nitroalkane and then, in situ Nef conversion.

Regioselective Annulation of 1,5-Diketones: Access to Functionalized Hagemann’s Esters

The synthesis of the “functionalized” Hagemann’s ester (S)-18 was investigated. The common starting material in these approaches was enamino ester (S,Z)-5, which was prepared through the condensation of keto diester 4 with (S)-1-phenylethylamine. The Michael addition reaction of 5 with methyl vinyl ketone gave the expected adduct (S)-6 with an ee ⩾ 95%. However, all attempts at annulation of 6 invariably afforded the unwanted cyclohexenone derivatives 7 or 8. The addition of 5 to Nazarov reagent 9 furnished adduct (S)-10 with an ee ⩾ 95%. The Triton B-induced annulation of 10 unexpectedly gave aldol 11. Depending on the reaction conditions, annulation of 11 afforded either the bicyclic lactone 12, or cyclohexenones 13 or 15. An efficient way of reversing the sense of the regiochemistry of the previous annulation was found, based on the use of diethyl 2-oxo-3-vinylphosphonate (16) as a Michael acceptor. Thus, the condensation of 5 with 16 gave (S)-17 with an ee ⩾ 95%, and cyclization of (S)-17 under Horner−Wadsworth−Emmons conditions gave the desired Hagemann’s ester (S)-18. The structural assignments for 18 were ascertained by chemical correlation with the known hydrindenedione (S)-21.

Annulation sequences employing methyl (E)- and (Z)-6-iodo-3-trimethylstannyl-2-hexenoates and related bifunctional reagents. Preparation of cisoidcis and cisoidtrans bicyclic dienes

A useful annulation method leading to the stereospecific synthesis of structurally novel, functionalized bicyclic dienes is described. Alkylation of 2-(methoxycarbonyl)cyclopentanone (34) and 2-(methoxycarbonyl)cyclohexanone (35) with methyl (E)- and (Z)-6-iodo-3-trimethylstannyl-2-hexenoates (27, 28) provided the keto diesters 36–39. Conversion of these substances into the corresponding enol triflates 47–50, followed by palladium(0)-catalyzed ring closure of the latter compounds, afforded the bicyclic dienes 55–58. In similar fashion, the keto esters 34 or 35 were transformed into the dienes 59–65. An X-ray crystallographic analysis of the p-nitrobenzoate 69, which was derived from the cisoidcis diene 64, showed that, in 69, the dihedral angle between the two carbon–carbon double bonds is −54.0(5)°.

The stereoselectivity of michael additions leading to enantiomerically pure indoloquinolizidones

AbstractAcylation of the carboline derivatives 6 and 9 with diketene affords the corresponding N‐(acetoacetyl)carbolines 7 and 10, respectively. While 10 can be converted into a 1:2.1 mixture of the title compounds 11 a and 11 b on treatment with oxalic acid, the cyclic acetal 7 can only be cyclized to yield the pyridone derivative 8. Michael addition of methyl malonate to the unsaturated ketone 11 b proceeds with excellent stereoselectivity to generate the keto diester 12 a which, on treatment with a base is transformed into its diastereoisomer 12 b. In contrast to 11 b, its stereoisomer 11 a does not react with methyl malonate.

Synthesis of (-) -Ambrox (R) from (-) -Levopimaric Acid

(-) -Ambrox (1) and (+) -8-demethylisoambrox (2), which give out a strong ambergris-type odor, were efficiently synthesized from (-) -levopimaric acid (3). The keto diester (8) was obtained by ozonolysis of methyl levopimalate. By the Wittig reaction, followed by epoxidation and reduction, the methyl and hydroxyl groups at C-8 were introduced. The triol (15) was convefted to the 8 α, 12-epoxy mesylate (16) by dehydration with methanesulfonyl chloride. The reduction of 16 with sodium iodide and zinc dust gave (-) -ambrox (1).

Reactions of Dimethyl (2'-Oxopropylidene)Propanedioate and Dimethyl (3'-Bromo-2'-oxopropylidene)propanedioate, Two Highly Electrophilic Trisubstituted Alkenes

The keto diester, dimethyl (2'-oxopropylidene)propanedioate, and its new 3'-bromo derivative have been made to react with a variety of nucleophilic reagents. Low molecular weight products have been obtained efficiently by processes involving conjugate addition, Diels-Alder reaction, Diels-Alder reaction having inverse electron demand, or ene reaction. Regiochemistry of the reactions is controlled by the dominant withdrawing effect of the two geminal ester groups. The amine addition products of the bromo keto diester were found to undergo a novel secondary dehydrobromination reaction under alkaline conditions.

ChemInform Abstract: CHEMISTRY OF THE PODOCARPACEAE. LXVI. PREPARATION AND REACTIONS OF DIMETHYL 13,14,15,16-TETRANORLABD-8(17)-ENE-12,19-DIOATE

Im Gegensatz zu früheren Versuchen läßt sich der ungesättigte Ester (Ib) leicht aus dem Keton (Ia) erhalten - Nebenprodukt ist das Lacton (III).

Chemistry of the Podocarpaceae. LXVI. Preparation and reactions of dimethyl 13,14,15,16-Tetranorlabd-8(17)-ene-12,19-dioate

The unsaturated diester (3) is conveniently prepared from the keto diester (2) by using a mixture of zinc, dibromomethane and titanium tetrachloride. Its synthetic utility and that of derived products has been explored.

Configuration and conformation of acyclic keto diesters

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConfiguration and conformation of acyclic keto diestersCharles A. Kingsbury, Ronald F. Hutton, and Dana DurhamCite this: J. Org. Chem. 1978, 43, 23, 4452–4458Publication Date (Print):November 1, 1978Publication History Published online1 May 2002Published inissue 1 November 1978https://doi.org/10.1021/jo00417a012RIGHTS & PERMISSIONSArticle Views67Altmetric-Citations3LEARN 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 (888 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: SYNTHESIS AND PROPERTIES OF 2,8‐DIOXABICYCLO(3.2.1)OCTANE DERIVATIVES

AbstractAus dem Säurechloridacetal (I) und dem Diester (II) wird über die Verbindungen (III) und (IV) die Dioxabicyclooctancarbonsäure (V) ‐ ein Abbauprodukt von Daphniphyllinsynthetisiert.

Synthesis and Properties of 2,8-Dioxabicyclo[3.2.1]octane Derivatives

Abstract In order to study the isomerization of daphniphylline into isodaphniphylline, 1,4-dimethyl-2,8-dioxabicyclo[3.2.1]octane-4-carboxylic acid (3), a degrada tion product of daphniphylline, was synthesized from the keto diester and transformed into the 3-oxacyclopentanones (6, 7).