The role of the 2-methyl substituent in governing stereoselective formation of the E isomer in the synthesis of 4-hydroxy-2-methyltamoxifen (1-{4-[2-(di-methylamino)ethoxy]phenyl}-1-(4-hydroxy-2-methylphenyl)-phenylbut-1-ene)
Syntheses of 4-hydroxy-2-methyltamoxifen (1-4-[2-(dimethylamino)ethoxy]phenyl}-1-(4-hydroxy-2methylphenyl)-2-phenylbut-1-ene) by dehydration of diastereoisomeric triphenylbutan-1-ol precursors were compared. Crystal structures of these diastereoisomers have now both been determined. Acid treatment of either diastereoisomer gave predominantly the E olefin (8:1 trans–cis), consistent with a mechanism