| Abstract
| - The treatment of N-acyl oxazolidinones of N-benzyl 2-indolecarboxylic acids varying in the substitutionpattern of the indole ring with samarium diiodide at −78 °C led to the formation of two indole dimerproducts. The major product isolated in yields from 55 to 59% represents an unsymmetrical dimer arisingfrom 1,4-addition to the 2-indolecarboxylic acid derivative of a possible ketyl-type radical anionintermediate originating from the reduction of the exocyclic carbonyl group of the N-acyl oxazolidinone.The minor dimer, represented by a symmetrical diketone, was produced in yields ranging from 11 to23%. Even in the presence of an α,β-unsaturated amide, dimerization was the preferred pathway ratherthan the formation of a γ-keto amide. Upon treatment with acid, the unsymmetrical indole dimer cyclizedto form a diindolequinone. Finally, the N-acyl oxazolidinones of pyrrole-2-carboxylic acid and3-indolecarboxylic acid preferred in both cases to undergo C−C bond formation with an acrylamide inthe presence of SmI2 rather than dimerization.
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