- COMPOUNDS
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The present invention relates to substituted pyridine compounds of Formula (I) and derivatives thereof, and to a process for preparing these substituted pyridines. The invention also relates to the use of the substituted pyridines as intermediates in the
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Page/Page column 37
(2008/06/13)
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- Synthesis of tetrasubstituted pyridines by the acid-catalysed Bohlmann-Rahtz reaction
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New facile experimental procedures for the preparation of 2,3,4,6-tetrasubstituted pyridines in a single synthetic step have been developed. Thus, an enamino ester and alkynone react by Michael addition-cyclodehydration in a heterocyclisation process that is catalysed by acetic acid, Amberlyst 15 ion exchange resin, zinc(II) bromide or ytterbium(III) triflate. The new one-step Bronsted or Lewis acid-catalysed Bohlmann-Rahtz reaction is a simple, direct and highly expedient method for the synthesis of pyridines that proceeds at a lower reaction temperature and avoids the need to isolate reaction intermediates.
- Bagley, Mark C.,Brace, Christian,Dale, James W.,Ohnesorge, Maren,Phillips, Nathan G.,Xiong, Xin,Bower, Justin
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p. 1663 - 1671
(2007/10/03)
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- Synthesis of pyridines and pyrido[2,3-d]pyrimidines by the Lewis acid catalysed Bohlmann-Rahtz heteroannulation reaction
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Lewis acids catalyse the Bohlmann-Rahtz heteroannulation reaction to generate highly functionalised pyridines from enamino esters and alkynones in a single synthetic step. Of the catalysts studied, ytterbium(III) trifluoromethanesulfonate and zinc(II) bromide are the two most efficient for the synthesis of pyridines and pyrido[2,3-d]pyrimidines, from ethyl β-aminocrotonate or 2,6-di-aminopyrimidin-4-one respectively, in up to 94% yield.
- Bagley,Dale,Hughes,Ohnesorge,Phillips,Bower
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p. 1523 - 1526
(2007/10/03)
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