An intramolecular Rauhut-Currier reaction utilizing alkynoates as the initial conjugate acceptor affords densely functionalized 5- and 6-membered rings from ynoate-enoate, ynoate-enenitrile, and alkynyl sulfone-enenitrile substrates. Trialkylphosphines catalyze the reaction, and TMSCN serves as a pronucelophile to effect turnover of the catalyst and the formation of a second C-C bond. Because of the highly electrophilic alkyne acceptor, this reaction yields products that cannot be easily accessed from the traditional Rauhut-Currier reaction.
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http://dx.doi.org/10.1021/jo3015769 | DOI Listing |
Chem Sci
December 2024
Department of Chemistry, Korea Advanced Institute of Science & Technology (KAIST) Daejeon 34141 Republic of Korea
Securinega alkaloids, known for their unique structures and neuroplasticity-inducing potential, are promising candidates for treating neurodegenerative diseases such as depression and substance use disorders (SUD). Herein, we delineate the total synthesis of two dimeric Rauhut-Currier (RC) reaction-based securinega alkaloids, (-)-flueggenine A and (-)-15'--flueggenine D. The key step involved a novel reductive Heck dimerization strategy, utilizing a silyl-tethered enone coupling partner to ensure the desired reactivity and stereoselectivity.
View Article and Find Full Text PDFChem Asian J
November 2024
State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China.
Herein, a facile head-to-tail dimerization of alkyl crotonates using electron-rich N,N'-bis(imidazolyl) guanidinylphosphines (BIG-Ps) as organocatalysts was firstly developed. This reaction proceeded smoothly under mild reaction conditions, effectively generating a series of functionalized 2-ethylidene-3-methylpentanedioates in excellent yields and stereoselectivity. Furthermore, this method was successfully applied for the synthesis of unsaturated polyesters by employing alkyl dicotonates as monomers.
View Article and Find Full Text PDFJ Org Chem
November 2024
Faculty of Sciences, Department of Chemistry, University of Chile, Las Palmeras 3425, Ñuñoa, 7750000 Santiago, Chile.
The synthesis of fused benzoxepines relies on the use of complex substrates and methodologies. Herein, we report our experimental and theoretical findings about an unprecedented Rauhut-Currier-type reaction catalyzed by CsCO to access these important compounds. The developed methodology avoids the use of phosphine- or amine-based catalysts and additives.
View Article and Find Full Text PDFJ Org Chem
September 2024
University of Rostock, Institute of Chemistry, Albert-Einstein-Str. 3a, Rostock 18059, Germany.
Dihydroazepino[1,2-]indole diones are tricyclic -acyl-2-alkylidene-3-oxindole enones that readily engage in tertiary phosphine-catalyzed intermolecular coupling reactions with acceptor-substituted alkenes. In these reactions, the tricyclic α-substituted enones undergo an α-alkylation with concomitant formation of a quaternary stereocenter, as well as the installation of a new double bond within the seven-membered azepane ring. The organocatalytic reaction constitutes a special case of the crossed intermolecular Rauhut-Currier reaction as the presence of the α-substituent in the enones prohibits the formation of an α,β-unsaturated product, but instead, skipped β,γ-unsaturated enones are obtained.
View Article and Find Full Text PDFOrg Biomol Chem
July 2024
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, S. A. S. Nagar, Punjab 140306, India.
We describe the first phosphine-promoted intramolecular Rauhut-Currier reaction that triggers an intramolecular Wittig process assembling new classes of diquinanes. The one-pot strategy provides ready access to simple diquinanes and various (hetero)arene-fused diquinanes incorporated with up to two contiguous all-carbon quaternary centers under metal-free and neutral conditions. We showcased the generality of the method on a broad range of substrates and demonstrated its synthetic utility in accessing various advanced intermediates relevant to natural product synthesis and material science.
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