Efficient synthesis of isoxazoles and isoxazolines from aldoximes using Magtrieve™ (CrO2)

A Facile One-Pot Synthesis of 3,5-Disubstituted Isoxazole Derivatives Using Hydroxy (Tosyloxy) Iodobenzene

“…Reaction with 4‐chlorobenzaldehyde oxime (0.50 g, 3.21 mmol) and ethyl propiolate (0.65 mL, 6.42 mmol) afforded compound 4b (0.45 g, 56%) as a white solid, mp 135–137°C (lit : 136–138°C); 1 H NMR (300 MHz, DMSO‐ d 6 ): δ 7.77 (d, J = 9.0 Hz, 2H. phenyl), 7.46 (d, J = 9.0 Hz, 2H, phenyl), 7.22 (s, 1H, isoxazole), 4.46 (d, J = 6.0 Hz, 2H, CH 2 ), 1.43 (t, J = 7.2 Hz, 3H, CH 3 ); 13 C NMR (75 MHz, CDCl 3 ) δ 162.1, 161.3, 156.8, 136.8, 129.5 (2C), 128.2 (2C), 126.6, 107.3, 62.5, 14.3; HRMS (ESI+) calcd.…”

“…However, the use of halogenating reagents for the synthesis of asymmetric 3,5‐disubstituted isoxazoles involves a two‐step synthetic protocol necessitating an additional base treatment and the need for temperature control to optimize reaction yields. Direct oxidizing agents such as ceric ammonium nitrate, lead (IV) acetate, potassium ferricyanide, magtrieve (CrO 2 ), and manganese dioxide have also been used to yield asymmetric 3,5‐disubstituted isoxazoles . However these reagents also suffer from certain disadvantages that include harsh reaction conditions, leading to the formation of significant amounts of corresponding aldehydes from aldoximes thereby lowering the overall yields of this reaction.…”

Emeraldine Base Form of Polyaniline Nanofibers as New, Economical, Green, and Efficient Catalyst for Synthesis of Z-Aldoximes

“…Oximes and their derivatives are important intermediates in the synthesis of amides [1][2][3][4], nitro compounds, hydroximinoyl chlorides, nitrones [5], amines, azoles, nitrile oxides, chiral -sulfinyl oximes, nitriles [6][7][8], and isoxazolines [9].…”

Isoxazole derivatives as new nitric oxide elicitors in plants

“…3,5-Disubstituted isoxazoles 6 , 7 , 9 and 10 (Table 1) have been previously prepared by different synthetic procedures, but compounds 6 [52], 7 [49] and 10 [53] have been only partly characterized, while for compound 9 [54] no characterization data have been reported.…”