Azide ring-opening-ring-closure reactions and tele-substitutions in vicinal azidopyrazole-, pyrrole- and indolecarboxaldehydes
作者:Jan Becher、Per Lauge Joergensen、Krystian Pluta、Niels J. Krake、Birgitte Falt-Hansen
DOI:10.1021/jo00033a039
日期:1992.3
5-Chloro-1-methylpyrazole-4-carboxaldehydes 1 react with excess sodium azide in dimethyl sulfoxide to produce a mixture of 1-azidomethyl-4-cyanopyrazoles 2 and 4-cyano-5-hydroxy-1-methylpyrazoles 3. Application of this reaction to the corresponding 5-chloro-1-phenylpyrazole-4-carboxaldehydes 5 gave 4-cyano-5-hydroxy-1-phenyl-pyrazoles 7 as the sole products in high yields. Likewise, 2-aryl-5-chloro-1-methylpyrrole-3,4-dicarboxaldehydes 9 rearranged to 2-aryl-4-cyano-5-hydroxy-1-methylpyrrole-3-carboxaldehydes 10 in high yields. In the indole series, treatment of 1-aryl-2-chloroindole-3-carboxaldehydes 11 with NaN3 yielded a mixture of 1-aryl-3-cyano-2(3H)-indolones 13 and 1-aryl-5-azido-3-cyanoindoles 12, both products resulting from a ring-opening-ring-closure reaction with concomitant nucleophilic tele-substitution at the 5-position of the indole ring.
Syntheses of<i>o</i>-Aminohetarenecarbaldehydes via Azides
作者:Jan Becher、Krystian Pluta、Niels Krake、Klaus Brøndum、Nils Just Christensen、Maria Victoria Vinader
DOI:10.1055/s-1989-27307
日期:——
o-Chlorohetarenecarbaldehydes react with sodium azide at low temperature yielding moderately stable o-azidohetarenecarbaldehydes. With hydrogen sulfide these compounds are reduced to the corresponding stable o-amino aldehydes. Both reaction steps give high yields.