| Autor: |
Galenko EE; Institute of Chemistry , Saint-Petersburg State University , Universitetskii pr. 26 , St. Petersburg 198504 , Russia., Novikov MS; Institute of Chemistry , Saint-Petersburg State University , Universitetskii pr. 26 , St. Petersburg 198504 , Russia., Shakirova FM; Institute of Chemistry , Saint-Petersburg State University , Universitetskii pr. 26 , St. Petersburg 198504 , Russia., Shakirova JR; Institute of Chemistry , Saint-Petersburg State University , Universitetskii pr. 26 , St. Petersburg 198504 , Russia., Kornyakov IV; Institute of Chemistry , Saint-Petersburg State University , Universitetskii pr. 26 , St. Petersburg 198504 , Russia., Bodunov VA; Institute of Chemistry , Saint-Petersburg State University , Universitetskii pr. 26 , St. Petersburg 198504 , Russia., Khlebnikov AF; Institute of Chemistry , Saint-Petersburg State University , Universitetskii pr. 26 , St. Petersburg 198504 , Russia. |
| Abstrakt: |
An effective strategy was developed for the synthesis of new 2,2'-bipyridine ligands, symmetrical and unsymmetrical 6,6'-binicotinates, and 2,2'-bipyridine-5-carboxylates, from 4-propargylisoxazoles. The synthesis of symmetrical 2,2'-disubstituted 6,6'-binicotinates was achieved using the Eglinton reaction of 5-methoxy-4-(prop-2-yn-1-yl)isoxazoles with Cu(OAc) 2 , followed by Fe(NTf 2 ) 2 /Au(NTf 2 ) tBuXPhos-catalyzed isomerization of the so-formed mixture of isoxazole/azirine-substituted biacetylenic intermediates. Unsymmetrical 2,2'-disubstituted 6,6'-binicotinates were prepared via a copper-free Sonogashira coupling of 5-methoxy-4-(prop-2-yn-1-yl)isoxazoles with 6-bromonicotinates to give methyl 6-(3-(5-methoxyisoxazol-4-yl)prop-1-ynyl)pyridine-3-carboxylates, followed by a transformation of the propargylisoxazole moiety of the adduct into the pyridine fragment under Fe(II)/Au(I) relay catalysis conditions. 6-(Pyrid-2-yl)nicotinates were synthesized by a Stille-type coupling of 2-(tributylstannyl)pyridine with 6-bromonicotinates. Several cyclopalladated complexes of a new series of 6,6'-binicotinates and 2,2'-bipyridine-5-carboxylates and the homoleptic Cu(I) complex were synthesized in high yields. |
