The reaction of α-chlorooximes or the isomeric nitrosochlorides with keto-stabilized dimethylsulphonium or triphenylarsonium ylides affords trans-5-acyl-Δ2-isoxazolines (VIIa- m) in good yields. The NOCI adducts of ethylpropenyl ether and ethylstyryl ether on reaction with dimethylsulphonium phenacylide lead directly to the corresponding 3-substituted-5- benzoylisoxazo] es. Dimethylsulphonium carbethoxymethylide on reaction with 2-chloro-2 ...