Determination of the relative stereochemistry of 5α- and 5β-diastereomers of [2α,3β,3aα]-ethyl hexahydro-2- (1,2,3,4- tetraacetoxybutyl)- 5,6,6- trimethylpyrrolo[1,2-b] isoxazole-3- carboxylate

(±)‐4,5,5‐Trimethyl‐1‐pyrroline‐1‐oxide reacted readily with ethyl 4,5,6,7‐tetra‐O‐acetyl‐trans‐2,3‐dehydro‐2,3‐dideoxy‐L(−)‐arabinoheptenoate in anhydrous benzene to give a mixture of two diastereomeric isoxazolidines, [2α,3β,3aα,5α]‐ and [2α,3β,3aα,5β]‐ethyl hexahydro‐2‐(1,2,3,4‐ tetraacetoxybutyl)‐5,6,6‐trimethylpyrrolo[1,2‐ b] isoxazole‐3‐carboxylate. The structures and configurations of both diastereomers were determined through the use of the (1H–1H) COSY, (13C–1H) HETCOR and NOEDS techniques.