Howard E. Zimmerman (1926-2012)

American chemist, professor at the University of Wisconsin–Madison from 1960. In 1957, with Marjorie D. Traxler, he proposed that the reactions of metal enolates with aldehydes (the Ivanov and Reformatsky reactions) proceed through a cyclic chair transition state: the Zimmerman–Traxler model, which explains the relationship between enolate geometry and aldol stereochemistry.

He was one of the founders of mechanistic organic photochemistry: he discovered the di-π-methane rearrangement and developed the Möbius–Hückel concept for pericyclic reactions.

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