Synthesis and configuration of diastereomeric 1-(β-dimethylaminoethyl)-2,5-dimethyl-4-plperidols
Diastereomeric 1-(β-dimethylaminoethyl)-2,5-dimethyl-4-piperidols were synthesized and their configurations were studied. The spatial orientation of the substituents in the α, β, and γ isomers of 2,5-dimethyl-4-piperidol was established, and the stereochemistry of the reduction of 2,5-dimethyl-4-piperidone with sodium in alcohol, with lithium aluminum hydride, and by catalysis on Raney nickel was studied by PMR spectroscopy. A series of transformations at the nitrogen atom of the piperidine ring do not change the configuration of 2,5-dimethyl-4-piperidols, but the stereochemistry of the reduction of the keto group in 2,5-dimethyl-4-piperidones with lithium aluminum hydride depends markedly on the character of the substituent attached to the piperidine nitrogen.