Intramolecular 1,3-Dipolar Cycloaddition of Nitrile N-Oxide Accompanied by Dearomatization

Abstract

Intramolecular 1,3-dipolar cycloaddition of 2-phenoxybenzonitrile N-oxides to benzene rings, accompanied by dearomatization, formed the corresponding isoxazolines in high yields. The X-ray single-crystal structure analysis revealed that the reaction formed the cis-adduct as a single isomer. The substituents on the benzene rings markedly affected the reaction rate, yield, and structure of the final product.

Convenient Synthesis of Pyrazolo[4′,3′:5,6]pyrano[4,3-c][1,2]oxazoles via Intramolecular Nitrile Oxide Cycloaddition

“…Notably, the intramolecular nitrile oxide cycloaddition (INOC) reaction can provide a route for the preparation of isoxazoles or isoxazolines annulated to various carbo- or heterocycles. For example, the intramolecular 1,3-dipolar cycloaddition of 2-phenoxybenzonitrile N -oxides to neighboring benzene rings, accompanied by dearomatization, formed the corresponding isoxazolines in high yields [ 14 ]. Recently, a method for the stereoselective synthesis of novel isoxazoline/isoxazole-fused indolizidine-, pyrrolizidine- and quinolizidine-based iminosugars has been developed, employing N -alkenyl/alkynyl iminosugar C -nitromethyl glycosides as nitrile oxide precursors in 1,3-dipolar cycloaddition reactions [ 15 ].…”

Pd Catalysis in Cyanide-Free Synthesis of Nitriles from Haloarenes via Isoxazolines

“…We reasoned that synthesizing an isoxazoline bearing a suitable tether would intramolecularly trap the coproduct and thus corroborate our rationale. The candidate of choice appeared to be polycyclic isoxazoline 8 (Scheme ) despite its propensity to readily deliver oxime 10 even at room temperature in basic medium . The expected arylnitrile 9 features a stable, tethered phenol fragment isolobal to the unstable and elusive ketosuccinate, and its formation would further substantiate our proposal.…”

Fluorescent poly(boron enaminoketonate)s: synthesis via the direct modification of polyisoxazoles obtained from the click polymerization of a homoditopic nitrile N-oxide and diynes

“…Building upon our previous study, [24][25][26][27][28][29][30][31][32][33][34][35][36] we selected bis(2-alcoxy-naphthalene nitrile N-oxide) as a skeleton, speculating that it should serve well as a framework for a sufficiently-stabilized homoditopic nitrile N-oxide. Synthesis of the homoditopic nitrile N-oxide 1 was accomplished in 58% overall yield via a three-step reaction (Scheme 1, m.p.…”