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Intramolecular reaction
About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.
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89 citations
TL;DR: The stepwise AdE-reaction of dicobalt hexacarbonyl complexes of conjugated enynes has been extended to include unsaturated electrophiles and nucleophiles to produce products with an orientation conducive to a subsequent conversion into polycyclic compounds via an intramolecular Khand-Pauson type reaction as discussed by the authors.
89 citations
TL;DR: Polymer-supported, palladium-catalyzed cyclization reactions effectively synthesized indolecarboxylates with various functional groups on the benzene ring through tandem Heck-amination reactions.
Abstract: Polymer-supported, palladium-catalyzed cyclization reactions effectively synthesized indolecarboxylates. Palladium-catalyzed carbon−carbon bond-forming reactions of immobilized enaminoesters followed by transesterification yielded indole 2- or 3-carboxylates with various functional groups on the benzene ring. Indolecarboxylates were efficiently cyclized via an intramolecular palladium-catalyzed amination reaction of immobilized N-substituted dehydrohalophenylalanines, and immobilized N-acetyl-dehydroalanines were efficiently converted into indolecarboxylates via tandem Heck−amination reactions.
89 citations
TL;DR: In this paper, an unstable associate of the 6-cis and 2,6-dicis-2-4 retinals and bacterioopsin is formed, possibly allowed by the lack of the cyclohexyl ring and thus the greater flexibility of the chromophore.
Abstract: samples at 80 K. The C-C band at 1558 cm-' represents the initial all-trans pigment while that at 1575 cm-* almost certainly arises from the short-wavelength M-type intermediate absorbing at ca. 380 nm. The results agree with previously determined correlation between A, and C=C stretching frequency and expected temperature dependence of M formation.12 On combination of the 6-cis and 2,6-dicis isomers of 2-4 with bacterioopsin, a broad absorption is noted with a A, , of 450-460 nm with a shoulder at 510 nm. Extraction of the pigment with methylene chloride yields the respective 6-cis or 2,6-dicis isomer. These pigments are rapidly (5 min) destroyed by hydroxylamine or all-trans-retinal. On irradiation, the absorption shifts to 487 nm, increases in intensity, and is identical with that of the all-trans pigments. Only the respective all-trans isomer is obtained when these irradiated pigments are extracted with methylene chloride. These results indicate that an unstable associate of the 6-cisand 2,6-dicis-2-4 retinals and bacterioopsin is formed, possibly allowed by the lack of the cyclohexyl ring and thus the greater flexibility of the chromophore. The above experiments demonstrate that these acyclic chromophores can form pigments with bacterioopsin which show light-induced absorption and pH changes. As these retinal derivatives lack both a cyclohexyl ring and the fifth C=C, neither of these structural elements are evidently essential for these functions of the pigment. A similar but more restrictive conclusion has been proposed for the 5,6-ethylene bond by our studies of the 5,6-dihydroretinal pigments.13 These results are consistent with isomerization and charge separation being thd primary event14 and indicate that the proton pumping and photocycling are dependent on the polyene chain portion of the retinal chromophore.
89 citations