The synthesis of spiro[cyclopropane-1,3'-oxindole]-2-carboxylic acid, including novel 3-(2- and 3-pyridyl)-substituted analogues and the novel cyclopropa[c]quinoline-7b-carboxylic acid and their ester and amide derivatives is described. These syntheses involve diastereoselective cyclopropanation reactions of methyl 2-(2-nitrophenyl)acrylate and (3E)-(pyridin-2-ylmethylene)- and (3E)-(pyridin3-ylmethylene)-1,3-dihydro-2H-indol-2-one with ethyl (dimethyl sulfuranylidene) acetate (EDSA). The synthesis of methyl cyclopropa[c]quinoline-7b-carboxylate involves a regioselective reductive cyclization of a nitro-diester precursor. The relative stereochemistry of key compounds has been determined by single-crystal X-ray structural analysis. (c) 2006 Published by Elsevier Ltd.
Yong, S. R., Ung, A. T., Pyne, S. G., Skelton, B., & White, A. (2007). Syntheses of spiro[cyclopropane-1,3'-oxindole]-2-carboxylic acid and cyclopropa[c]quinoline-7b-carboxylic acid and their derivatives. Tetrahedron, 63(5), 1191-1199. https://doi.org/10.1016/j.tet.2006.11.051