Arthur Lapworth. The genesis of reaction mechanism

Abstract

Examines the contributions made by Arthur Lapworth to the mechanistic view of organic reactions.

Logic of organic chemistry

“…They install an alternating acceptor-donor reactivity network (pattern) along the carbon skeleton (backbone). This concept is very old and was probably generalized for the first time by Lapworth in 1898 [3,4]. This natural reactivity is depicted in Scheme 2.…”

“…From this Scheme can be seen that donor carbon atoms are characterized by even numbers, whereas acceptors have odd numbers (Schemes 3, 4). By inspection of donors a following reactive scheme can be drawn: d 2 , d 4 , d 6 to d n A similar network can be developed for acceptors: a 1 , a 3 , a 5 to a n .…”

“…There is only one disconnection and thus in general two synthetic possibilities to synthesize 1,2 difunctional compounds ( Schemes 3,4). An example is given by the synthesis of a-hydroxy ketones in Scheme 19. Butyraldehyde is naturally reacting as an a 1 acceptor.…”

“…Again we start with the decarboxylative bromination of the c-lactone (compare with Scheme 80) [46]. The resulting a 4 acceptor is converted into the corresponding d 4 donor. This ''umpolung'' was realized by means of zinc.…”

The Stories of Santonin and Santonic Acid

“…By the time Woodward tackled the santonic acid problem, giving it his almost undivided attention in the early months of 1943,22 the mechanisms of a large number of base‐catalyzed reactions had been elucidated, most notably through the ground‐breaking achievements of Arthur Lapworth 23. Systematically and exhaustively, Woodward analyzed the consequences of addition of hydroxide ion to each of the several electrophilic carbon atoms in santonin and the consequences of removal of acidic hydrogen atoms, no matter how weakly they might appear to be activated.…”