Norcamphor ketals

Table 3 Hydrogenolysis of Mixed Ketals of Norcamphor by HAICh in Ether at Room Temperature ...

Norcamphor isobutylene ketal appears (NMR) to be a nearly equal mixture of the isomers (21) and (22) (Scheme 6), but it is reduced as though it were only (21), reacting via a retention mechanism. The reduction is very slow (168 h) and it is this author s view that one cannot exclude the possibility that (22) is not reduced at all but is isomerized to replace (21) as it is consumed (a few such isomerizations have been observed). 

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