HYDROGENATION OF SYN- AND ANTI-7-ACETOXYNORBORNENES AND 7-ACETOXYNORBORNADIENE OVER PLATINUM AND PALLADIUM CATALYSTS

A study of the hydrogenation of syn- and anti-7-acetoxynorbomenes, 7-acetoxynorbomadiene, and related compounds over various platinum and palladium catalysts has been made. A marked sensitivity of these reductions to catalyst, catalyst prereduction, and the steric requirements of the 7 substituents has been observed. In addition to the anticipated reduction products, the hydrogenation of 7-acetoxynorbornadiene has yielded 3- acetoxynortricyclene in amounts ranging from 3-5% over platinum catalysts to 25-30% over prereduced palladium catalysts. Reductions utilizingdeuterium have shown that the dienyl acetate and syn-7-acetoxynorbornene experience substantial endo,cis deuteriumaddition as well as the normally anticipated exo,cis addition. The anti-acetate reduces exclusively through exo,cis addition. The relative rates of syn and anti double-bond reduction, kanti/ksyns, for syn- and anti-acetoxynorbomenes and for 7-acetoxynorbomadiene have shown that, while reduction of the monoolefins is largely controlled by steric effects, the reduction of the dienyl acetate is less sensitive to steric factors. A rationale for these observations is attributed to the direction of coordinationof the olefinic substrates with the catalyst. The hydrogenation of norbornadiene and 7-acetoxynorbornadiene over prereduced palladium has revealed the anomalous behavior of the prereduced catalyst. © 1969, American Chemical Society. All rights reserved.