GEORGE JUST, GRANT READER, and BERNADETTE CHALARD-FAURE. Can. J. Chern. 54, 849 (1976).The Diels-Alder adduct of cyclopentadiene and 8-brorno acrylic acid 1 was converted to ~,~-exo-6,7-(dihydroxy-di-O-isopropylidene)-2-hydroxy-3-oxabicyclo[3.2.1]octane (9) in an eight-step sequence and a 24% yield based on 1. Alternatively, the hemiacetal9 was obtained in five steps and 22% yield from norbornadiene through the intermediate lactone 11. The thiosernicarbazone and sernicarbazone of 9 were prepared. The synthesis of the free aldehyde 13 as well as that of the Wittig reaction products 12 and 19 are described. GEORGE JUST, GRANT READER et BERNADETTE CHALARD-FAURE. Can. J. Chern. 54, 849 (1976).La rkction de l'acide 8-bromo acrylique 1 sur le cyclopentadkne conduit au produit d'addition de Diels-Alder correspondant; ce dernier peut Ctre transformi en huit Ctapes avec un rendernent global de 24y0 bask sur 1 en D,L-exo-(dihydroxy-di-0-isopropylidene-6,7 hydroxy-2-oxa-3 bicyclo[3.2.l]octane 9. L'hCmiacCtal 9 a Cgalernent Ct C obtenu en cinq Ctapes avec un rendement de 22'g ? i partir du norbornadikne et en passant par la lactone 11. On d k r i t la preparation de la thiosernicarbazone et de la semicarbazone de 9 ainsi que la synthtse de 1'aldChyde 13 et des produits 12 et 19 provenant de rkctions de Wittig.In a preliminary communication (I), we reported the synthesis of lactol9 and lactone 11. In this paper, we are giving a full account of this work and the description of a second pathway leading to 9 and 11. The syntheses of related derivatives and of the free aldehyde 13 are also described. These compounds are potential intermediates for the preparation of carbocyclic analogues of C-nucleosides.Condensation of 0-bromoacrylic acid 1 with cyclopentadiene in benzene (2) gave the DielsAlder adduct 2 in 75% yield. This compound was almost exclusively the endo carboxylate isomer (3). Treatment of the acid 2 with diazomethane gave, in essentially quantitative yield, the ester 2a which was oxidized to the diol 3 with hydrogen peroxide and a catalytic (4) amount of osmium tetroxide. The diol3, mp 145 "C, was obtained in 50% yield. The stereochemistry of the hydroxy groups in 3 was assigned on the basis of previous work (4, 5) which had shown the preferential exo-hydroxylation of bicyclic[2.2.1] systems of type 2.Attempts to hydroxylate the acid 2 directly were unsuccessful. Crude diol3 was converted to its isopropylidene derivative 3a in 60% yield based on adduct 2. Elimination of hydrogen bromide by treatment of 3a with 1,Sdiazabicyclo[5.4.0]undec-Sene afforded the olefinic ester 4. Upon treatment of diol 3 with acetic anhydride -pyridine, the olefinic diacetate 4a was obtained. Similarly, the olefinic carbonate derivative 4b was the major product from the reaction of diol 3 with phosgene in pyridine. It was not possible to obtain a pure sample of 3a for elemental analysis, although the compound was otherwise well characterized. Attempts at purification by column chromatography, on either silica gel or alumina (activity 1 or...
GEORGE JUST and BERNADETTE CHALARD-FAURE. Can J. Chern. 54, 861 (1976). Condensation of lactone 1 and aminoguanadine provides the amino-triazole carbocyclic analogue of C-nucleoside 2a. Lead tetraacetate oxidation of the semicarbazone derivative 4 leads to the amino-oxadiazole derivative 5. Isoxazolines 11 and 12 are obtained by 1,3-dipolar addition of mesitonitrile oxide with the a,p-unsaturated ester 13. Addition of diazomethane onto ester 13 gives the pyrazoline 16 which can be oxidized with bromine to the corresponding carboethoxy-pyrazole 17. The latter is converted to the carboxamido-pyrazole 18 by treatment with ammonia.
Das Diels‐ Alder‐Addukt (IIIa) aus den Komponenten (I) und (II) wird über die Stufen (IIIb), (IVa), (IVb), (V), (VI), (VIIa) und (VIIb) in das Hemiacetal (VIIIa) übergeführt, das zum Lacton (VIIIb) oxidiert wird [Gesamtausbeute, bezogen auf (I), 22%].
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