We report aryne generation from 2-triazenylarylboronic acids using an activator such as Brønsted acids, Lewis acids, and solid acids. With the use of (±)-Camphorsulfonic acid [(±)-CSA], the aryne precursors provided cycloadducts with a range of arynophiles in high yields. Aryne generated under the acidic conditions underwent chemoselective cycloaddition with a furan in the presence of a basic arynophile, namely an amine. Hammett plot analyses revealed that an aryne generation mechanism induced by (±)-CSA is distinct from the mechanism induced by silica gel.
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http://dx.doi.org/10.1248/cpb.c22-00264 | DOI Listing |
J Org Chem
January 2025
Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan.
Arynes are important synthetic intermediates that are usually generated under alkaline conditions. We developed a method for generating arynes using two hydroxy compounds as activators. -Triazenylarylboronic acids generate (hetero)arynes when activated by a combination of ethylene glycol, pinacol, and -nitrophenol; these arynes then react with a range of arynophiles under slightly acidic conditions that complement the conventional basic conditions with unique chemoselectivities observed even in the presence of excess hydroxy compounds.
View Article and Find Full Text PDFThe hexadehydro-Diels-Alder (HDDA) reaction is a cycloisomerization between a conjugated diyne and a tethered diynophile that generates -benzyne derivatives. Considerable fundamental understanding of aryne reactivity has resulted from this body of research. The multi-yne cycloisomerization substrate is typically pre-formed and the (rate-limiting) closure of this diyne/diynophile pair to produce the isomeric benzyne generally requires thermal input, often requiring reaction temperatures of >100 °C and times of 16-48 h to achieve near-full conversion.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, Massachusetts 02138, United States.
Chem Asian J
December 2024
Department of Chemistry, Ramakrishna Mission Residential College (Autonomous) Narendrapur, Narendrapur, Kolkata, 700 103, West Bengal, India.
The article reports a hitherto-unknown aromatic proton transfer (APT) to the o-amine function chelated to manganese(II) ion and disintegration of the molecule generating an aryne intermediate. The reaction of (NQ)-NH(AQ) (LH) with manganese(II) acetate in boiling DMF generates [Mn(L)], where the LH ligands undergo disintegration forming manganese(II) complexes of AQ and an 1,4-naphthoquinonyne intermediate based on benzoquinone ring, that has been defined as [NQ-2H] (NQ and AQ abbreviate respectively 1,4-naphthoquinone and 8-aminoquinoline fragments). The fragmentation reaction of LH depends on the metal precursor used, solvent and temperature.
View Article and Find Full Text PDFJ Org Chem
January 2025
School of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006, P. R. China.
In this study, a metal-free and efficient method for the synthesis of sulfilimines and -sulfanylanilines in high yields with excellent chemoselectivities from oxonium aryne precursors with sulfenamides has been developed. This method features mild reaction conditions, simple operations, a general substrate scope, and good tolerance of functional groups. In addition, scale-up synthesis, related applications, and preliminary mechanistic explorations were also investigated.
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