A Novel Entry to 17α-Bromo- and 17α-Iodoethynyl Steroids
About: This article is published in Angewandte Chemie.The article was published on 1984-09-01. It has received 196 citations till now.
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TL;DR: In this paper, a review of recent progress in the synthesis and characterization of well-defined conjugated polymers and oligomers is presented using a subdivision into three main sections, covering hydrocarbon polymers, heterocyclic polymer and the oligomers, respectively.
297 citations
TL;DR: Based on the trends in the spectroscopic behaviour of those molecules with increasing chain length, electronic as well as the NMR properties of carbyne are predicted, in line with the previously reported results.
Abstract: Three series of differently 3,5-disubstituted alpha,omega-diphenylpolyynes Ar-(C[triple bond]C)n-Ar (n=2, 4, 6, 8, 10) were synthesized under optimized Cadiot-Chodkiewicz conditions, isolated and completely characterized. These compounds can be considered as model substances for the hypothetical one-dimensional carbon allotrope carbyne Cx. The longest sp-carbon chain contains 20 atoms and is therefore the longest, purely organic polyyne studied with NMR techniques. Extinction coefficients over 600,000 M(-1) cm(-1) represent the highest measured quantitative values for that compound class so far. Comparisons with previous investigations and electrochemical studies allow the assignment of absorption for both wavelength regions structuring the UV/Vis spectra. Based on the trends in the spectroscopic behaviour of those molecules with increasing chain length, electronic as well as the NMR properties of carbyne are predicted, in line with our previously reported results. The observed stability properties promise the synthesis of even longer polyynes.
216 citations
TL;DR: In this paper, the ruthenium catalyst exhibited metathesis activity for a range of substrates, including alkyls, alkarnes, Ph, CO2Me, SnBu3, TMS, Cl, Br, I.
Abstract: Ruthenium carbene 1 (Cl2(PCy3)2RuCHCHCPh2) mediates the efficient and selective conversion of acyclic dienynes to fused bicyclic [n.m.0] rings containing five-, six-, and seven-membered rings. Studies with various X-substituted acetylenes (X = H, alkyls, Ph, CO2Me, SnBu3, TMS, Cl, Br, I) suggest that the dienyne metathesis is sensitive not only to these substituents but also to the catalysts employed. Among the various metal alkylidenes examined, only the ruthenium catalyst 1 exhibited metathesis activity for a range of substrates. These observations further expand the scope of catalytic RCM for the construction of complex organic compounds.
210 citations
TL;DR: This work gratefully acknowledges the University of California, Berkeley, NIHGMS (R01 GM073932-01), Merck Research Laboratories, Bristol-Myers Squibb, Amgen Inc., DuPont, GlaxoSmithKline, Eli Lilly & Co., Pfizer, AstraZeneca, and Roche for financial support.
Abstract: [*] S. T. Staben, J. J. Kennedy-Smith, D. Huang, B. K. Corkey, R. L. LaLonde, Prof. Dr. F. D. Toste Department of Chemistry University of California Berkeley, CA 94720 (USA) Fax (+1)510-643-9480 E-mail: fdtoste@uclink.berkeley.edu [**] We gratefully acknowledge the University of California, Berkeley, NIHGMS (R01 GM073932-01), Merck Research Laboratories, Bristol-Myers Squibb, Amgen Inc., DuPont, GlaxoSmithKline, Eli Lilly & Co., Pfizer, AstraZeneca, and Roche for financial support. J.J.K.-S. thanks Eli Lilly & Co. for a graduate fellowship. We thank Lauren A. Young for the preparation of tributylallenylstannane. Supporting information for this article is available on the WWW under http://www.angewandte.org or from the author. Angewandte Chemie
207 citations
TL;DR: In this paper, the title compound was synthesized as its racemate in 33 steps using an intramolecular Diels−Alder reaction (see Scheme 5, 24 → 25) to provide control over the eventual cis C4−C7 relationship.
Abstract: The title compound has been synthesized as its racemate in 33 steps. An intramolecular Diels−Alder reaction (see Scheme 5, 24 → 25) was used to provide control over the eventual cis C4−C7 relationship. The installation of another cis related ethynyl group at C2 arose from transformation 40 → 42 (see Scheme 8) whose directionality is governed by a benzophenone ketal functioning as a temporary steric control unit. Closure of the enediyne unit was accomplished on a trimethylsilylethoxycarbonyl (TEOC) protected dihydroquinoline derivative. It involved use of a novel bis-iodoalkyne/distannylethylene interpolative coupling transformation (61 + 58 → 63, Scheme 12). In the terminal phase of the synthesis, a novel iminoquinone ketal 74 (Scheme 15) was condensed with homophthalic anhydride derivative 78 (Scheme 16) as indicated in Scheme 17. The final deprotection involved cleavage of a methoxymethyl ester and two methoxymethyl phenol ethers. From this work, there arose the concept and demonstration of p-quinone mo...
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