Notiz über die Acyloinkondensation einiger Pyridinaldehyde

Mathes, Wilhelm; Sauermilch, Walter; Klein, Theo

doi:10.1002/cber.19540871212

Cited by 15 publications

(1 citation statement)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have found only two reported reactions in which selenium dioxide causes the opening of a five-membered heterocyclic ring, involving the benzoxazole (21) and the dihydropyrazole (22).' The former reaction was performed with selenium dioxide in aqueous dioxane, and could be a simple hydrolysis, particularly since the corresponding benzthiazole was not reactive.…”

mentioning

confidence: 99%

Triazolopyridines. Part 6. Ring opening reactions of triazolopyridines

Jones¹,

Mouat²,

Tonkinson³

1985

J. Chem. Soc., Perkin Trans. 1

View full text Add to dashboard Cite

The triazole ring in 1,2,3-triazolo[l,5-a] -pyridinesand -quinolines, and in 1,2,3-triazoIo[5,1 -a3 isoquinolines can be opened with loss of nitrogen. The reagents described are bromine, aqueous sulphuric acid, glacial acetic acid, and selenium dioxide; the products from the triazolopyridines are dibromomethyl, hydroxymethyl, acetoxymethyl, and acyl derivatives of pyridine. The generality of the reactions is discussed. The first reported reaction in which the six-membered ring of a 1,2,3-triazolo[l,5-a]pyridine is opened, by hydride reduction, gives a triazolyl butadiene.We have reported in previous parts of this series that the triazolopyridine (la), triazoloquinolines (2) and (3), and triazoloisoquinoline (4) undergo directed lithiation which can lead to regiospecific substitution on the six membered rings. When this type of substitution can be combined with a good procedure for opening the triazole ring, with loss of nitrogen, we have syntheses of 2,6-disubstituted p y r i d i n e ~, ' ~ of 2,3disubstituted q u i n o l i n e ~, ' ~~ and of 1,3-disubstituted isoquinolines.' Most of our syntheses have involved the use of bromine for the ring opening, giving for example 2-dibromomethylpyridine (6a) which was easily converted into pyridine-2carbaldehyde,6 but restrictions with this reaction led us to study other ring opening procedures. This study has much widened -2

show abstract

mentioning

confidence: 99%