- Siloxane-Based Cross-Coupling of Bromopyridine Derivatives: Studies for the Synthesis of Streptonigrin and Lavendamycin
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(Equation Presented) Highly functionalized 4-bromopyridines were prepared and found to undergo fluoride-promoted, Pd-catalyzed cross-coupling with aryltrialkoxy-silanes to give sterically demanding biaryls. The 3-nitro-4-bromopyridine derivative coupled i
- McElroy, William T.,DeShong, Philip
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p. 4779 - 4782
(2007/10/03)
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- Synthesis of 4-methoxy-2,3,5-trimethylpyridine: a specific building block for compounds with gastric-acid inhibiting activity.
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A new synthesis of 4-methoxy-2,3,5-trimethylpyridine (2), an important building block for the preparation of gastric-acid inhibiting compounds, is described. Condensation of ethyl 3-amino-2-methyl-2-butenoate (3) and diethyl 2-methylmalonate (4) gives 4-hydroxy-3,5,6-trimethyl-2(1H)-pyridone 5. Reaction of 5 with phosphoryl chloride affords 2,4-dichloro-3,5,6-trimethylpyridine (9a), which, upon hydrogenolysis with palladium on charcoal, gives 2,3,5-trimethylpyridine (10). However, selective hydrogenolysis in acidic solution yields 4-chloro-2-3-5-trimethylpyridine (11). Substitution of the chlorine in 11 with methoxide ion gives 4-methoxy-2,3,5-trimethylpyridine (2), which can be oxidized to the corresponding N-oxide (13). This constitutes a new and efficient route to compound 2 in an overall yield of 43%.
- Mittelbach,Schmidt,Uray,Junek,Lamm,Ankner,Br?ndstr?m,Simonsson
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p. 524 - 529
(2007/10/02)
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