- Regioselective Pd-Catalyzed Synthesis of 2,3,6-Trisubstituted Pyridines from Isoxazolinones
-
Substituted pyridines are prevalent heterocycles of fundamental importance. Their efficient regioselective preparation is often still a challenge despite a large number of reported synthetic methodologies. In this letter we report an operationally simple approach that makes use of readily accessible isoxazolinones. The protocol involves a Pd(II)-catalyzed C-regioselective 1,4-addition to vinylketones, followed by a Pd(0)-catalyzed transformation, which is assumed to proceed via vinylnitrene-Pd intermediates. Both hydrogen and air are necessary for the pyridine formation step and could be employed at ratios above the upper explosive limit thus avoiding a safety issue. This new strategy allows an effective, scalable and practical access to various previously unknown 2,3,6-trisubstituted pyridines.
- Rieckhoff, Stefan,Hellmuth, Tina,Peters, René
-
-
Read Online
- Chemistry of 5(2H)-Isoxazolones: C-Alkylation and a New Route to 3a,5,6,7a-Tetrahydro-4H-pyranoisoxazoles
-
The first evidenceof C-alkylation in substituted 5(2H)-isoxazolones during a Michael reaction and alkylation with methyl iodode is presented.Some of the Michael adducts are used as starting materials for preparing cis-3a,5,6,7a-tetrahydro-4H-pyrano
- Batra, Sanjay,Seth, Manju,Bhaduri, Amiya P.
-
p. 1025 - 1046
(2007/10/02)
-