Rearrangement and cyclization reactions of carboxylic acids and esters

Ketonic Decarboxylation Catalysed by Weak Bases and Its Application to an Optically Pure Substrate

“…This is probably due to the formation of disodium adipate, which is not transformed into cyclopentanone. This result is in agreement with published results indicating that sodium salts, in general, give poor results for the ketonic decarboxylation [3] and that salts of adipic acid give low yields, as already mentioned above. The residue, in this case a white-brownish solid, can be re-used and employed instead of the base, i.e.…”

“…(1) Although ketonic decarboxylation has been known for more than 140 years (dry distillation of calcium acetate to produce acetone), [2] the mechanism is still under discussion. [3] This might be the reason why so many different catalysts have been proposed as promoters for this reaction. In general, thorium oxide is recommended as catalyst for the ketonic decarboxylation.…”

Ketonization of Carboxylic Acids by Decarboxylation: Mechanism and Scope

“…For instance, when reacting dimethyl octanedioate in the presence of alumina, cycloheptanone is obtained in a regular yield of 29% (Table 8, entry 6) as opposed to 69% in the case of cyclopentanone (Table 6, entry 8). At the [45] (5 mol-%) 6 3 -tert-butyl 350 Na 2 CO 3 83 [45] (5 mol-%) 7 2,2-dimethyl 225 [a] Na 3 PO 4 77 [46] (23 mol-%) 8 2,2-dimethyl 225 [a] Na 2 B 4 O 7 80 [47] (19 mol-%) 9 2,2,5,5-tetramethyl 320-340 KF anhydrous 52 [15] (45 mol-%) 10 2,2,5,5-tetramethyl 320-330 BaO 72 [15] (15 mol-%)…”

“…An excellent and detailed historical overview can be obtained from the literature. [9] The Mechanism and Corresponding Experimental Support…”

“…The many different early versions of the reaction − i.e., the great diversity of promoting materials employed in varying amounts and reactions performed in the presence of water or under strictly anhydrous conditions − confused chemists, especially when they began to determine the mechanism. [8,9] At the time, they were unable to distinguish between ketonic decarboxylation, ketonic decarboxylation under forced reaction conditions involving side reactions, Scheme 1. Results of the ketonic decarboxylation of adipic acid conducted in the presence of different amounts of barium hydroxide and water and oxidative decarboxylation.…”