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The inherent high reactivity and color instability of primary amines has limited their applicability in polyisocyanate-based coatings. However, recent developments in the use of modified amine functional coreactants in such formulations shows significant progress towards having two-component systems with excellent application and durability properties. The systems reviewed here use amine functional groups which are either blocked by addition of carbonyl compounds, or are of reduced reactivity through steric hindrance and intramolecular hydrogen bonding. The relative benefits and drawbacks of the various systems are detailed along with their applicability to high solids coatings.

The cycloaddition reactions of several phenylsulfonyl-substituted allenes with diazomethane have been investigated. The major products formed were identified as 3-(phenylsulfonyl)-4-methylene-2-pyrazolines. These pyrazolines engage in a variety of mechanistically interesting transformations, ranging from base-catalyzed rearrangements to addition of Grignard regents. The dipolar cycloadduct derived from the reaction of diazomethane with 3-(phenylsulfonyl)-1,2-butadiene undergoes a 1,3-phenylsulfonyl shift upon irradiation to give 3-methyl-4-[(phenylsulfonyl)methyl] pyrazole. The cycloadduct derived from the reaction of 2,3-bis(phenylsulfonyl)-1-propene with diazomethane readily loses nitrogen upon photolysis to give 1-[(phenylsulfonyl)methyl]-1-(phenylsulfonyl)cyclopropane

Le traitement du 2,3-dibromo-1-benzenesulfonyl-1-propene avec des composes β-dicarbonyles en presence de methoxyde de sodium conduit avec un haut rendement au furane bicyclique 2,4-disubstitue et au furane bicyclique 2,3-fusionne. La formation du cycle furane implique une sequence d'addition-elimination, une deacetylation et des reactions de deplacement de type SN2

2,3-Dihalo-1-(phenylsulfonyl)-1-propenes, obtained by the addition of bromine or iodine onto (phenylsulfonyl)propadiene, were found to exhibit interesting reactivity as both mono- and dielectrophiles, with the mode of reactivity depending upon the nature of the nucleophile as well as the reaction conditions. Thus, amines or thiophenols smoothly effected substitution at the allylic site, while sodium methoxide reacted at the vinylic position through an addition-elimination process

2,3-Dihalo-1-(phenylsulfonyl)-1-propenes, obtained by the addition of bromine or iodine onto (phenylsulfonyl)propadiene, were found to exhibit interesting reactivity as both mono- and dielectrophiles, with the mode of reactivity depending upon the nature of the nucleophile as well as the reaction conditions. Thus, amines or thiophenols smoothly effected substitution at the allylic site, while sodium methoxide reacted at the vinylic position through an addition-elimination process

Radical attack on the double bond of 2,3-bis(phenylsulfonyl)-1-propene leads to an intermediate sulfonyl stabilized radical. This species readily fragments to produce a new vinyl sulfone which can undergo further radical cyclization to give a six ring sulfone.

Le traitement du 2,3-dibromo-1-benzenesulfonyl-1-propene avec des composes β-dicarbonyles en presence de methoxyde de sodium conduit avec un haut rendement au furane bicyclique 2,4-disubstitue et au furane bicyclique 2,3-fusionne. La formation du cycle furane implique une sequence d'addition-elimination, une deacetylation et des reactions de deplacement de type SN2

Les cycloadditions dipolaires 1,3 de l'[arylidene hydroxytrimethylsilyl] ammonium (A) sont etudiees. Selon la nature du dipolarophile, (A) se comporte soit comme une nitrone soit comme un ylure d'ammoniomethanure