Abstract
The reductions of 1-phenyl-3-hydroxyimino-5-methyl-2-pyrrolidinone, using i) Platinum dioxide in glacial acetic acid, ii) Raney nickel in Ethanol, and iii) Aluminum mercury in moist tetrahydrofuran, were carried out to furnish two isomeric amines, designated as IIa and 1-phenyl-3-amino-5-methyl-2-pyrrolidinone (IIb). Quantitative ratios of these amines formed as regard to the reduction methods allowed us to assign cis-configuration to IIb and trans-configuration to IIa. From the studies of ultraviolet and nuclear magnetic resonance spectra of the 3-hydroxy-compounds, 1-phenyl-3-hydroxy-5-methyl-2-pyrrolidinone (IIIa) and 1-phenyl-3-hydroxy-5-methyl-2-pyrrolidinone (IIIb), prepared from IIa and IIb respectively, the occurrence of Walden-inversion in the diazotization reaction was concluded. At the same time cis-configuration of IIb and IIIa was also predicted, which was supported by leading IIIa to cis-1-tosyl-2-methyl-4-methoxypyrrolidine (X) synthesized from dl-allo-hydroxyproline.
