3-Methyl-7-bromo triazolo

Chemical Name 8-Bromo-6-(o-chlorophenyl)-1-methyl-4H-s-triazolo-[3,4c] -thieno-[2,3e] -1,4-diazepine... 

In the frame of a medicinal chemistry program at Merck Sharp Dohme Ltd, Collins and co-workers reported successful Negishi cross-coupling reaction of 3-aryl-7-bromo-6-[( 1 -methyl-1/7-1,2,4-triazol-5-yl)methoxy][ 1,2,4]triazolo[4,3-/ pyridazines (63) with aliphatic organozinc reagents [35]. 

The first example of an alkynylation of a bicyclic pyridazine derivative was published in 2000 [35]. Collins studied Sonogashira coupling of 7-bromo-6-[(1-methyl-l//-l,2,4-triazol-5-yl)methoxy]-3-phenyl[l,2,4]triazolo[4,3-Z ]pyridazine (165) with propargyl alcohol at 90°C in a sealed tube using Pd(PPh3)4 and Cul in triethylamine. Unfortunately, only a low yield of the reaction product (202) was obtained. 

Bromination of 5-hydroxy-7-methyl-l,2,4-triazolo[4,3-c]pyrimidine (96) led to the introduction of the bromo function into the only available site in the pyrimidine ring (C8 of 96) to afford 97 (60G1821) (Scheme 42). 

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