A synthetic route involving a key Neberrearrangement is described for the preparation of both [1-13C] and [1-15N] DL-homophenylalanine (2-amino-4-phenylbutanoic acid), using suitably labelled sodium cyanide as the source of the isotopic label. These compounds have been prepared for use in studies on the biosynthesis of phenylethyl glucosinolate in Brassica napus. 3-Phenylpropanaldoxime, the initial
The acid-catalyzed rearrangement of 5-cyclodecynone (1) to bicyclo[4.4.0]-1(6)-decen-2-one (5) has been investigated via C-13 and deuterium labeling experiments, which showed that the transannular rearrangement proceeds by a mechanism not involving an enol of 5-cyclodecynone. Subjecting 5-cyclodecynone to NBS in ethyl ether resulted in the formation of a dibromooxetane 21 which arose from a bromo allylic alcohol 20 formed from 5-cyclodecynone and HBr. The chloro allylic alcohol 28 was formed from HCl and was subsequently converted to enone 5. Pathways were investigated using AM1 calculations. As a result, a modified mechanism consistent with all the experimental data is proposed for the acid-catalyzed rearrangement of 1 to 5.