H-1-NMR SPECTROSCOPIC STUDIES OF THE STABILITY OF AN OXAZOLIDINE CONDENSATION PRODUCT

Condensation of (-)-norephedrine with excess formaldehyde under mild c onditions leads to formation of the 2:1 condensation product N,N'-meth ylenebis(4-methyl-5-phenyl)oxazolidine compared with the reaction with 1 mol of formaldehyde, which leads to 4-methyl-5-phenyloxazolidine. H -1 and C-13 NMR spectroscopy was used to monitor the stability of this compound and its decomposition products. The 2:1 condensation product is found to be stable in CDC1(3) but breaks down rapidly in CD3OD to yield a 50:50 mixture of 4-methyl-5-phenyloxazolidine and 3-hydroxymet hyl-4-methyl-5-phenyloxazolidine. Upon addition of D2O to this equimol ar mixture, the latter compound decomposes to norephedrine and formald ehyde, whereas the former compound is stable. (C) 1997 by John Wiley & Sons, Ltd.