HIGHLY DIASTEREOSELECTIVE SYNTHESIS OF 2-OXAZOLINE-4-CARBOXYLATES BY FORMAL [3-ALKOXYOXAZOLE WITH ALPHA-ALKOXY ALDEHYDES CATALYZED BY TIN(IV) CHLORIDE(2] CYCLOADDITIONS OF A 5)

The formal [3 + 2] cycloaddition of 5-methoxy-2-(p-methoxyphenyl) oxaz ole with 2(S)-(benzyloxy)propanal and 2(S)-[(tert-butyldimethylsilyl)o xy]propanal in the presence of tin(IV) chloride gave cis-(4R,5S,1'S)- and (methoxycarbonyl)-2-(p-methoxyphenyl)-2-oxazolines with high diast ereoselectivity (94 and 92% selectivity, respectively). A similar reac tion of 5-methoxy-2-(p-methoxyphenyl) oxazole with 2,3-di-O-benzyl-D-g lyceraldehyde gave methyl ,2'-bis(benzyloxy)ethyl]-2-oxazoline-4-carbo xylate with high diastereoselectivity (>95% selectivity), and the latt er was easily converted to biologically important chiral 2-amino-1,3,4 ,5-tetrol derivatives.