A Highly Efficient Synthesis of a Naphthalenoid Histamine‐3 Antagonist

A highly efficient synthesis of the potent and selective histamine‐3 receptor antagonist 1A was accomplished in four chemical steps and a salt formation step in 36% overall yield from 6‐bromo‐2‐naphthalenol 9 . The key features are a regioselective Suzuki coupling protocol for selective vinylation of 12 with potassium vinyltrifluoroborate in high yield (92%) with excellent regioselectivity (90:2) and a base‐catalyzed hydroamination reaction of 11 in an anti‐Markovnikov fashion under mild reaction conditions. An optimized copper‐catalyzed cross coupling reaction is used to incorporate the pyridazinone 4 .