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Bohlmann-Rahtz Reaction. Student name:Fawzeya Khundaqgy. Content of the presentation. The object of the reaction Background Reaction and Mechanism Application and recent literature Conclusion References. The object.
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Bohlmann-Rahtz Reaction Student name:Fawzeya Khundaqgy
Content of the presentation The object of the reaction Background Reaction and Mechanism Application and recent literature Conclusion References
The object The Bohlmann-Rahtz Pyridine Synthesis allows the generation of substituted pyridines in two steps. Condensation of enamines with ethynylketones leads to an aminodiene intermediate that, after heat-induced E/Z isomerization, undergoes a cyclodehydration to yield 2,3,6-trisubstituted pyridines.
Background Bohlmann and Rahtz,in 1957,reported the preparation of 2,3,6-trisubstituted pyridines.Their method employes the Michael addition of acetylenic ketone with enamines .The aminoketones are typically isolated and subsequently heated at temp. greater than 120C to facilitate the cyclohydration .(1)
Reaction and Mechanism The reaction The first step of the mechanism
Application and recent literature A new one-step synthesis of pyridines under microwave-assisted conditions(4) A new mild method for the one-pot synthesis of pyridines(3)
A New Modification of the Bohlmann-Rahtz Pyridine Synthesis(5)
Conclusion • The Bohlmann-Rahtz reaction aims to produce substituted pyridine but recently there are some methodes that allow the synthesis of tri- and tetrasubstituted pyridines in a one step procedure with the acid catalyst that allow the cyclodehydration to proceed at asignificantly lower temperature
References (1)http://books.google.ps/books?id=4k0jI7Sf6iwC&pg=PA309&dq=bohlmann+reaction&hl=ar#v=onepage&q=bohlmann%20reaction&f=false (2)http://www.organic-chemistry.org/namedreactions/bohlmann-rahtz-pyridine-synthesis.shtm M. C. Bagley, J. W. Dale, J. Bower, Synlett, 2001, 1149-1151. (3) http://www.organic-chemistry.org/namedreactions/bohlmann-rahtz-pyridine-synthesis.shtm X. Xiong, M. C. Bagley, K. Chapaneri, Tetrahedron Lett., 2004, 45, 6121-6124.
(4) http://www.organic-chemistry.org/namedreactions/bohlmann-rahtz-pyridine-synthesis.shtm • M. C. Bagley, R. Lunn, X. Xiong, Tetrahedron Lett., 2002, 43, 8331-8334 (5)http://www.organic-chemistry.org/namedreactions/bohlmann-rahtz-pyridine-synthesis.shtm M. C. Bagley, J. W. Dale, J. Bower, Synlett, 2001, 1149-1151.