One-pot synthesis of highly functionalized pyridines via a rhodium carbenoid induced ring expansion of isoxazoles.
A concise one-pot synthesis of highly functionalized pyridines has been developed. The first step in the reaction sequence is the formal insertion of rhodium vinylcarbenoids across the N-O bond of isoxazoles. Upon heating, the insertion products undergo a rearrangement to give 1,4-dihydropyridines. DDQ oxidation then affords the corresponding pyridines in 31-84% yield. The process has proven general with a range of carbenoid and isoxazole components and represents a unique disconnection strategy for the synthesis of functionalized pyridines.
Manning
James R
JR
Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, USA.
Davies
Huw M L
HM
D004095:Dihydropyridines / Q000737:chemistry*; D006358:Hot Temperature; D007555:Isoxazoles / Q000737:chemistry*; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis*; D012238:Rhodium / Q000737:chemistry*
D004095:Dihydropyridines; D007555:Isoxazoles; D011725:Pyridines; C038806:1,4-dihydropyridine; D012238:Rhodium; D009584:Nitrogen; D010100:Oxygen