Grignard reagents 2-isoxazoline synthesis

Isoxazolin-5-one, 2,3-dimethyl-4-substituted photolysis, 6, 14 Isoxazolinones synthesis, 5, 132 Isoxazolin-3-ones alkylation, 6, 43 synthesis, 6, 106, 129 Isoxazolin-4-ones synthesis, 6, 106-107 Isoxazolin-5-ones alkylation, 6, 39 4,4-dialkyl substituted reaction with Grignard reagents, 6, 40 reactions with bases, 6, 41 synthesis, 6, 103-105 Isoxazolium bisulphate, 2,3,5-trimethyl-hydrogen exchange, 6, 21 Isoxazolium salts deprotonation, 5, 71 as hardeners for gelatin, 1, 363 nucleophilic cleavage, 6, 31 nucleophilic reactions, 6, 28-29 4/f-pyran synthesis from, 3, 761 reactions... 

The first synthesis of this compound to be completed was the result of studies by Smith and co-workers in 1982. The readily available flavor constituent cyclotene (368) (Scheme 2.28) was reduced and isomerized to 2-methyl-2-cyclopenten-l-one (369) in 64% yield. Addition of dimethyl cuprate followed by isomerization and Baeyer-Villiger oxidation gave the racemic 8-lactone 370 (86%). Addition of allyl Grignard reagent followed by formation of the methyl ketal provided a 71% yield of 371, which possesses the expected axial methoxy group. Conversion of the terminal olefin into the functionalized isoxazoline 373 was accomplished in 68% by the 1,3 dipolar cycloaddition of nitrile oxide 372. 

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