2-Substituted 3,4-unsubstituted isoxazolin-5-ones: synthesis and comparison with the natural compounds

Abstract

Various ways to substitute the nitrogen atom of isoxazolin-5-one are described. The properties of synthetic 2-substituted 3.4-unsubstituted isoxazolin-5-ones are compared with the natural compounds. The structure of the natural 2-(2-cyanoethyl)-3-isoxazolin-5-one has been proven by establishing its identity with the synthetic compound.A NUMBER of 2-substituted 3,4-unsubstituted isoxazolin-5-ones have been isolated from Pisum sativum and Lathyrus odoratus ~eedlings.l-~ They are the only known natural compounds with an isoxalin-&one ring. The confirmation of their chemical structure by synthesis was therefore desirable. Isoxazolin-5-one was first mentioned as a reaction product arising from nucleic acids by treatment with hydro~ylamine.~*~ Its synthesis and properties were described by De Sarlo? and on alkylation with diazomethane it gave 2-methyl-3isoxazolin-&one. This paper reports other ways to alkylate the nitrogen atom of isoxazolin-5-0ne.~ RESULTS AND DISCUSSIOKThe isoxazolin-5-one anion (1) was alkylated by ally1 bromides, dialkyl sulphates and toluene-$-sulphonates. Cyanoethylation of isoxazolin-5-one (1) was achieved with acrylonitrile. Only strong alkylating agents could substitute the isoxazolin-5-one anion (1). Dialkyl sulphates react readily, while toluene-p-sulphonates react rather slowly. Alkyl iodides, ethyl chloroacetate, and

Synthesis and photosensitivity of isoxazolin-5-one glycosides

“…Isoxazolin-5-one derivatives of glucose, β-aminopropionitrile and amino acids occur as secondary metabolites in different plant-and insect families. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] 2-(β-D-Glucopyranosyl)-3-isoxazolin-5-one (1) is one of the major components of the defensive secretions of diverse leaf beetle species (Chrysomelina). 7,[10][11][12][13] Seedlings of a variety of plants within the legume family (Fabaceae) contain high amounts of this compound during development and growth.…”

A tale of four kingdoms – isoxazolin-5-one- and 3-nitropropanoic acid-derived natural products

“…Syntheses of N-substituted 3-isoxazolin-5-one derivatives were achieved using the sodium salt of the heterocycle 30. 59,72,119,120 The latter compound was synthesized starting from ethyl propiolate 41 via ethyl 3-(hydroxyimino)propanoate 42 (Fig. 10a).…”

“…10b). 59,119 This observation is in part due to the low selectivity of these reactions, which leads to the formation of 3-, 4-as well as O-substituted derivatives of 3-isoxazolin-5one. 119 A further attempt where O-acetylserine reacted with isoxazolin-5-one under catalysis by pyridoxal phosphate provided BIA 11 in a very low yield of 0.15%.…”

“…59,119 This observation is in part due to the low selectivity of these reactions, which leads to the formation of 3-, 4-as well as O-substituted derivatives of 3-isoxazolin-5one. 119 A further attempt where O-acetylserine reacted with isoxazolin-5-one under catalysis by pyridoxal phosphate provided BIA 11 in a very low yield of 0.15%. 121 Thus, an alternative method for the synthesis of 3,4-unsaturated 3-isoxazolin-5-one derivatives was developed by Baldwin and coworkers, based on a 5-endo-dig reaction.…”

Chemical Constituents from Dendropanax dentiger

“…The 1 H NMR spectrum (CD 3 OD, 600 MHz) also showed two-sets of signals. That belonging to 20 showed two olefinic protons at δ 5.30 and 8.41 (each d, J = 3.5 Hz), characteristic for a 3-isoxazolin-5-one moiety [26]. The HMBC spectrum showed the correlations of glc H-1 (δ 4.89, d, J = 9.1 Hz) / C-3 (δ 154.8) and of H-4 (δ 5.30) and H-3 (δ 8.41) / C-5 (δ 173.9).…”