Phenyl-ethyl, hydrogenolysis

Under alkaline conditions isolating lignin degradation products which are essentially of a phenyl.ethyl rather than a phenylpropyl nature is structurally important and requires a lignin structure by which the 7-carbon may be removed as a result of a 0-7 carbon-carbon cleavage reaction, either by direct alkaline hydrolysis or alkali-catalyzed hydrogenolysis. 

The reactions catalyzed by rhodium are quite different from those with cobalt. For example, the results with methyl 3,3-dimethacrylate indicate a destabilizing effect of the ester group, leading mainly to hydrogenolysis since isomerization occurs less readily with rhodium than with cobalt. Moreover, the nature and the position of the substituents seem to have little influence on the alkvlrhodiumcarbonyl stability. This attenuates the effect of the ester group, as shown by the results with methyl tiglate, methyl cinnamate, and ethyl 3-phenyl-2-butenoate. 

Bonner et al. found that the hydrogenolysis of optically active methyl or ethyl atrolac-tates (48, X = OH) in refluxing ethanol with large amounts of Raney Ni proceeded largely with retention of configuration methyl D-(+)-2-phenyl-2-methoxypropionate... 

The aziridine (212) is converted into the ethyl 2-phenyl-l//-benz[d]azepine-4-carboxylate on heating in toluene <86JCS(P1)1113>, and hydrogenolysis of the aziridine (213) affords the tetra-hydrobenz[d]azepine (214) <86H(24)2099>. 

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