Donald N. Kline

Isoxazoline oxidation. An efficient method for the preparation of α,β-unsaturated carbonyl compounds

Abstract MCPBA peracid oxidation of Δ 4 -isoxazolines derived from the dipolar cycloaddition reaction of nitrones with acetylenes or allenes produces α,β-unsaturated ketones in excellent yield.

Dipolar cycloaddition reaction of (phenylsulfonyl)propadiene with nitrones and alkylation studies of the cycloadducts

Abstract Dipolar cycloaddition of nitrones with (phenylsulfonyl)propadiene give 4-sulfonyl substituted isoxazolidines whose reactions with base and several electrophiles have been studied.

Use of 2,3-(diphenylsulfonyl)-1-propene as an allene equivalent in cycloaddition chemistry

Abstract The cycloaddition chemistry of 2,3-(diphenylsulfonyl)-1-propene with several nitrones has been investigated. The reagent formally corresponds to an allene equivalent.

Alkylation studies of 5-exo-methylene substituted isoxazolidines

1,3-bipolar cycloaddition of nitrones to phenylsulphonylallene gives in high yield and with complete regiospecificity 5-methyleneisoxazolidines. These on treatment with base and subsequent reaction with electrophiles afford both α- and γ-substituted products. With methyl iodide as the electrophile, only the α-methylated product was isolated. In contrast, reaction of the 5-exo-methylene-4-phenylsulphonylisoxazolidine with allyl bromide afforded the γ-allylated product. Formation of this was shown to be via direct γ-attack, rather than by α-attack, followed by a 3,3-sigmatropic rearrangement. Further studies show that the product ratio is controlled by a sensitive interplay between thermodynamic and steric factors and is very dependent on the nature of the electrophile used.