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[摘要]：Compounds (More Than One Hetero Atom)) Section Several representative acetylenic sulfones were immobilized on a polymer support derived from Merrifield resin by means of ester linkers that were used to couple free carboxylic acid groups on the solid support with benzylic hydroxyl functions on the arylsulfonyl moieties of the acetylenes. Several examples of reversed ester linkers, using Merrifield resin directly, were also successfully prepd. The 1,3-dipolar cycloaddns. of the solid-supported acetylenic sulfones were investigated with a series of 1,3-dipoles, including benzyl azide, Et diazoacetate, diazomethane, as well as representative nitrile oxides, nitrile imines, nitrile ylides, nitrones, azomethine imines, azomethine ylides, munchnones, and sydnones. In general, analogous cycloaddns. were also performed with acetylenic sulfones in soln. phase for comparison. The cycloaddns. typically afforded good to excellent yields of the desired products in both soln. and solid phase, although the latter reactions sometimes required more vigorous conditions. Except in the case of benzyl azide and diazo compds., where mixts. of regioisomers were obtained, the other 1,3-dipoles reacted with high regioselectivity and afforded essentially unique regioisomers. Cleavage of the products from the resin was smoothly effected by alk. hydrolysis, while several attempts at reductive desulfonylation with sodium amalgam or samarium diiodide-HMPA resulted in N-O or C-O scission, in addn. to cleavage from the polymer. The method provides access to a no. of important classes of heterocycles, including variously substituted and functionalized triazoles, pyrazoles, 1,2-oxazoles, pyrroles, as well as their dihydro and bicyclic analogs. The success of the cycloaddns. on polymer supports paves the way to future investigations of sequential transformations leading to libraries of useful heterocycles. |
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