Oxazolidine ring, N-condensed

N-Condensed oxazolidine ring from cyclic 2-iminoalcohols... 

The same group prepared N-(/S-D-glucopyranosyl)oxazolidine-2,4-diones [146] and N-(/l-D-glucopyranosyl)imidazolidine-2,4-diones [147] by desulfurization-condensation of glucosyl isothiocyanate with a-hydroxyacids and J -substituted a-aminoacids, respectively, in the presence of silver triflu-oroacetate and triethylamine. 4-Glucosyl-l,2,4-oxadiazolidine-5-thiones were also prepared by reaction of protected glucosyl isothiocyanates with an ox-aziridine ring [148]. 

Reissert s compound (l-cyano-l,2-dihydroquinolinyl benzamide) is apparently de-protonated under phase transfer conditions at the one-carbon as expected. The condensation of the carbanion with an aldehyde or ketone leads to an N-benzoyl alk-oxide in which oxygen acylation (N ->0 acyl transfer) results in five-membered ring formation. The intermediate oxazolidine decomposes with loss of cyanide to give the benzoate ester of an isoquinolinoylcarbinol as shown in equation 10.26 [36]. 

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