J8-Propiolactone

Dialkyl dimethyl phosphoramidites (16) react with j8-propiolactone to give the phosphoramidate (17) and the phosphonate (18), A kinetic study suggests a mechanism involving initial attack of phosphorus at saturated carbon to give (17), while a four-centred transition state (19) is invoked to explain the formation of (18). 

When /J-ethynyl-j8-propiolactone (I) is the substrate, allenic 3,4-alkadienoic acids (2) are obtained in high yield. The reaction has been used for a synthesis of pcllitorine (3). 

A novel method consists in reacting a j8-propiolactone with 5-alkyl isothiouronium salts127 to give 2-imino-4-oxotetrahydro-l,3-oxazines. 

A similar reaction with diphenylketene101 yields an analog of 24. Diphenylketene also cycloadds to some heterocycles containing a C=N bond102 to form fused 1,3-oxazine rings. l,3-Oxazin-4-one is also formed by condensation of a j8-propiolactone with p-nitrobenzylideneaniline at 130° to 135°C in the presence of sodium acetate.103... 

What is the structure of the polymer produced by anionic polymerizaiior of j8-propiolactone using NaOM as catalyst ... 

Treatment of 2-methylthioimidazoline (653) with /3-trichloromethyl-j8-propiolactone (654) produced (655), presumably by initial iV-acylation and then cyclization to form the oxazine ring (69JOU1790). 

Carboxyethylation of enamines occurs on heating with j -propiolactone. A <5-keto-carboxylic acid amide is produced directly in high yield in the absence of water (Scheme 65). The same product was obtained on replacing j8-propiolactone by acrylic acid, and saturated carboxylic acids gave cyclohexanone and the corresponding carboxylic acid amide. 

Molecular dynamics of j8-propiolactone (PL) homopolymer and its block copolymer with j8-butyrolactone (BL) in the solid state have been investigated by broad-line and pulse NMR [141]. 

In the ketene method, j8-propiolactone is heated with methanol and alkyl sulfate (or dialkyl sulfate) to 100-200°C to eliminate water, thereby yielding methyl acrylate. 

With j8-propiolactone, an acetyl scission has also been discussed. The anionic polymerization of 8-caprolactone probably also occurs by an acyl ring opening ... 

Carboxybetaines have been prepared by reacting a fluorinated tertiary amine with /3-propiolactone [182-186], chloroacetic acid or its sodium salt [185-194] or acrylic acid [182,185,186]. j8-Propiolactone is a suspected carcinogen and is probably no longer used commercially as a quaternizing agent. 

Because j8-propiolactone is a suspected carcinogen, sodium chloroacetate (or chloroacetic acid) has become the preferred alkylation agent ... 

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