4-piperidinone 2 2 6 6-tetramethyl- July 8, 2019 16 32 64 128 4 piperidinone 2 2 6 6 tetramethyl 4 4 6 6 '- tetramethyl 2 2 '- bipyridine 4 4'-dimethyl-2 2'-bipyridine 4 4'-dimethyl-2 2'-bipyridyl 4 4'-di-tertbutyl-2 2'-bipyridine 4 4'-bipyridine
