Über die Umsetzung von 1-Phenylpyrazol mit Äthylmagnesiumbromid. 8. Mitteilung über Grignard-Reaktionen [1]

✍ Scribed by Adrian Marxer; Max Siegrist

• Publisher: John Wiley and Sons
• Year: 1974
• Tongue: German
• Weight: 683 KB
• Volume: 57
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19740570711

✦ Synopsis

Abstract

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.