Synthesis of 3-Alkyl Oxazolidines, Derived from 2-Hydroxymethyl Piperidine, as Analytical Standards for the Analysis of Volatile Aldehydes in the Workplace.

Hexahydro-3-alkyl-3-oxazolo[3,4-]pyridines for the quantitative analysis of various aldehydes were obtained in good yield the condensation reaction of 2-hydroxymethylpiperidine (2-HMP) with aldehydes under mild conditions. When acrolein was used, the bicyclic was obtained. This novel compound has suitable physical characteristics for an analytical standard. The hexahydro-3-vinyl-3-oxazolo[3,4-]pyridine can be obtained at higher temperatures using an excess of acrolein (3 equiv). Following the same procedure as for , but with an excess of 2-HMP (2 equiv), a diastereomeric mixture of /, which are both bisadducts of 2-HMP with acrolein, was obtained. The latter mixture can be easily converted into pure . Mechanistically, a thorough H-NMR study did not show any evidence that the condensation reaction proceeded an enamine. The reaction probably proceeded through an elusive hemiaminal and fleeting iminium ion, which underwent subsequent cyclization to give hexahydro-3-alkyl-3-oxazolo[3,4-]pyridines -. The reaction pathways for the preparation of are described.