Transannular Cannizzaro reaction

G. Mehta and co-workers unexpectedly encountered a novel transannular Cannizzaro reaction when 1,4-bishomo-6-seco[7]prismane dialdehyde derivative was subjected to basic conditions to yield a novel octacyclic lactone. " The transannular Cannizzaro reaction is the result of the proximity of the two reacting aldehyde groups induced by the rigid caged structure. 

Mehta, G., Padma, S. Observation of a transannular Cannizzaro reaction in a caged [7]prismane related system. J, Org, Chem, 1991,56, 1298-1299. 

The latter results from an unusual intramolecular Cannizzaro-tjrpe reaction involving a transannular hydride transfer from C-20 to C-7. Oxidation of LXXVI followed by reduction gave the epimeric hydroxyl lactam LXXVII with the hydroxyl (p ax 1682 cm i) in the original configuration of ajaconine. The hydroxyl in LXXVI is thus trans to the i r-bridge and in LXXVII is cis thereto. Further evidence on this point is provided by the behavior of the methiodide (LXXVIII) of the azo-methine alcohol (LXVII). The product liberated from this salt by hot, methanolic alkali is a hydroxyl-free base (LXXIX, 10) and hence... 

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See also in sourсe #XX -- [ ]

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