Generation and hydrolysis of N-acyloxazolinium salts allowing regiospecific acylation of chiral amino alcohols

In an attempt to form 2-alkylidene-1,3-oxazolidines, chiral 2-oxazolines have been N-alkylated and N-acylated. Two new N-methyloxazolinium salts have been prepared and characterised but base treatment resulted in their decomposition. In contrast, attempts to isolate three N-benzoyloxazolinium salts gave the products of their ring hydrolysis: unsymmetrically diacylated amino alcohols whose structure was confirmed by x-ray diffraction in one case. Overall the method allows stepwise regiospecific N,O-diacylation of 1,2-amino alcohols.