One‐Pot Preparation of 3‐Arylisoxazole‐4,5‐dicarboxylates from Benzylic Chlorides and Acetylenedicarboxylates

Abstract

Various diethyl 3‐arylisoxazole‐4,5‐dicarboxylates were efficiently prepared in good to moderate yields by the successive treatment of benzylic chlorides and alkyl p‐tosylates with N‐methylmorpholine N‐oxide (NMO) and then hydroxylamine hydrochloride and potassium carbonate followed by Oxone® and diethyl acetylenedicarboxylates. This one‐pot proccess was carried out under mild, transition‐metal‐free conditions.

A Copper‐Catalyzed Synthesis of Pyrroles through Photochemically Generated Acylazirines

“…The spectroscopic data are in accordance to the literature. [19] 3-(4-Fluorophenyl)-5-phenylisoxazole (3e). Following the general procedure using 4-fluorobenzaldehyde (8.32 mmol, 0.89 mL, 1.00 equiv.)…”

Naphtho[1,8-de][1,2]Oxazin-4-ol: Precursor to 1,2,8-Trisubstituted Naphthalenes and 1-Unsubstituted Naphtho[1,2-d]isoxazole 2-Oxide: A Novel Isomerization of the N-Oxide to Nitrile Oxide en Route to Isoxazol(in)es

“…Compound 22: (118 mg, 12%) as an orange oil; R f = 0.38 (20% EtOAc in hexane); 1 H NMR (400 MHz, CDCl 3 ) δ: 7.97 (d, J = 9.1 Hz, 1H), 7.73-7.66 (m, 2H), 7.66-7.57 (m, 2H), 7.53-7.31 (m, 9H), 7.06 (dd, J = 7.6 Hz, 1.2 Hz, 1H), 5.47 (s, 4H); 13 (24) This was prepared according to the experimental procedure for the synthesis of ( 13) from (5) (Scheme 2). Used as starting material of compound (23) (400 mg, 5 mmol, 1 equiv), MeI (724 mg, 5.1 mmol, 1.02 equiv) Na 2 CO 3 (540 mg, 5.1 mmol, 1.02 equiv), acetone (15 mL) and H 2 O (3 mL), which gave the title compound (384 mg, 93%) as a yellow solid, m.p.…”

“…Dialkyl 3-(napththalen-1-yl)isoxazole-4,5-dicarboxylates were obtained by a 1,3-dipolar cycloaddition of a (naphthalene-1-yl)nitrile oxide in situ, with the appropriate dialkyl acetylenedicarboxylate. The reactions differ by the generation mode of the nitrile oxide from the 1-naphthaldehyde oxime, by the use of PIDA [ 23 ] and oxone ® [ 24 , 25 , 26 , 27 ], or by chlorination and then dehydrochlorination [ 28 ]. 5-Aryl-3-(naphthalene-1- or 2-yl)isoxazoles have been prepared by the oxidative aromatization of 5-aryl-4,5-dihydro-3-(naphthalene-1 or 2-yl)isoxazoles [ 29 , 30 ].…”

Recent Advances in the Oxone-Mediated Synthesis of Heterocyclic Compounds

“…In 2018, Imai and Togo reported an Oxone-mediated synthesis of 3-arylisoxazole-4,5-dicarboxylates 89, through the one-pot reaction between benzylic chlorides 80 or alkyl 4-tosylates 91, and acetylenedicarboxylate 50p (Scheme 57) [56]. The substrates 90 and 91 were treated with N-methylmorpholine N-oxide (NMO, 4 equiv), and then with hydroxylamine hydrochloride (1.2 equiv) and potassium carbonate (0.6 equiv), followed by the addition of acetylenedicarboxylate 50p, to generate desired products 89.…”