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Über die Umsetzung von 1‐Phenylpyrazol mit Äthylmagnesiumbromid. 8. Mitteilung über Grignard ‐Reaktionen [1]
Author(s) -
Marxer Adrian,
Siegrist Max
Publication year - 1974
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19740570711
Subject(s) - chemistry , pyrazole , medicinal chemistry , magnesium bromide , yield (engineering) , deprotonation , grignard reaction , methanol , butyllithium , ring (chemistry) , bromide , magnesium , organic chemistry , reagent , ion , materials science , metallurgy
In contrast to butyllithium, ethylmagnesium‐bromide reacts with 1‐phenyl‐pyrazole exclusively by deprotonation, at the ortho position of the phenyl‐ring. With nitriles the intermediate 2‐(1‐pyrazolyl)‐phenylmagnesiumbromide gave good to excellent yields of 1‐(2‐aroyl or 2‐hetaroyl‐phenyl)‐pyrazoles (Table 1, compounds 5a – 5i ); with ketones the corresponding methanol derivatives (Table 2, compounds 6a – 6c ) were found, whilst CO 2 yielded the corresponding 1‐(2‐carboxyphenyl)‐pyrazole ( 3 ). Surprisingly enough, 1‐( o ‐bromo‐phenyl)‐pyrazole and magnesium did not yield a single product, but a mixture of 3 compounds, which on reaction with 4‐benzoylpyridine gave the three alcohols 19 , 20 and 21 .