The synthesis of various substituted bicyclic lactams by an acid-induced Pictet-Spengler reaction of tetrahydroindolinones bearing tethered heteroaromatic rings is presented. The outcome of the cyclization depends on the position of the furan tether, tether length, nature of the tethered heteroaromatic ring, and the substituent group present on the 5-position of the tethered heteroaryl group. A one-pot procedure was developed to efficiently prepare tetrahydroindolinones containing tethered furan rings. In a typical example, the reaction of furanyl azide 26 with n-Bu3P delivered iminophosphorane 27, which was allowed to react with a 1-alkyl-(2-oxocyclohexyl)acetic acid to provide the desired furanyl-substituted tetrahydroindolinone system 29. Treatment of 29 with trifluoroacetic acid afforded the tetracyclic lactam skeleton 30 found in the alkaloid (+/-)-selaginoidine.
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http://dx.doi.org/10.1021/jo0619783 | DOI Listing |
Angew Chem Int Ed Engl
November 2024
Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN, 47401, US.
A strategy for the photosensitized [2+2]-cycloaddition between styrenyl dihaloboranes and unactivated allylamines to access cyclobutylboronates with control of stereochemistry and regiochemistry is presented. The success of the reaction relies on the temporary coordination between in situ generated dihaloboranes and amines under mild reaction conditions. In addition, cyclobutanes with varying substitution patterns have been prepared using N-heterocycles as directing group.
View Article and Find Full Text PDFChem Asian J
December 2024
School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China.
Polycyclic heteroaromatics (PHAs) are a highly versatile class of functional materials, especially applicable as efficient luminophores in organic light-emitting diodes (OLEDs). Those constructed by tethered phenyl surrounding the main group center attract extensive attention due to their excellent OLED device performance. However, the development of such a class of emitters is often limited to boron, nitrogen-doped π-conjugated heterocycles.
View Article and Find Full Text PDFOrg Lett
January 2024
Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States.
J Org Chem
January 2021
Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
An efficient weak carboxylate-assisted oxidative cross-dehydrogenative C-H/C-H coupling (CDC) of heteroarenes with readily available olefins has been devised employing water as green solvent under ruthenium(II) catalysis. The reaction is operationally simple, accommodates a large variety of heteroaromatic carboxylic acids as well as olefins, and facilitates a diverse array of high-value olefin-tethered heteroarenes in high yields (up to 87%). The potential of this -C-H bond activation strategy has also been exploited toward tunable synthesis of densely functionalized heteroarenes through challenging unsymmetrical bis-olefination process in a one-pot sequential fashion.
View Article and Find Full Text PDFJ Org Chem
April 2020
Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey.
A facile and efficient method for the synthesis of 3-[(4-nitrophenyl)thio]-substituted 4-methylene-1-pyrrolines is described. When treated with 4-nitrobenzenesulfenyl chloride in refluxing acetonitrile, -propargylic β-enaminones produced α-sulfenylated -propargylic β-enaminones, which, in the presence of sodium hydride or cesium carbonate, underwent nucleophilic cyclization to afford 4-methylene-3-[(4-nitrophenyl)thio]-1-pyrrolines in good to high yields. It was shown for the first time that on -propargylic β-enaminone systems, α-sulfenylation dominates over the formation of thiirenium ion.
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