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Phosphoramides, XV. Phosphorus pentoxide amine mixtures as reagents in the synthesis of 2‐(dialkylamino)quinolines
Author(s) -
Hansen Bo W.,
Pedersen Erik B.
Publication year - 1981
Publication title -
liebigs annalen der chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0170-2041
DOI - 10.1002/jlac.198119810820
Subject(s) - chemistry , formamides , phosphorus pentoxide , amine gas treating , nucleophile , formamide , organic chemistry , isoquinoline , reagent , acetanilide , ring (chemistry) , phosphorus , medicinal chemistry , catalysis
2‐(Dialkylamino)quinolines were prepared by treating acetanilides and N,N ‐dialkylformamides with a mixture of phosphorus pentoxide and a dialkylamine at 250°C. A mechanism which is related to HMPT induced ring closure reactions is proposed. Proper choice of amine and formamide is important, because transacylation reactions take place. The cleanest reaction was obtained if the amine used and the amine, which could be liberated from the formamide, were identical, or if the former amine has the greater nucleophilicity. Sterical hindrance in the ring closing step may occur. Formates, instead of formamides, can also be used.