3 Spiro epoxyazetidin 2 ones

Durst and Sharma [86] have reported the stereospecific synthesis of 3-spiro-epoxyazetidin-2-ones 55 (Scheme 14). The oxidation of the diastereoisomers of compound 52 with PCC provided a single acetyl compound 3-acetyl-3-benzyloxy-azetidin-2-one 53. Nonchelation controlled L-Selectride reduction of 53 gave the isomerically pure 3-hydroxyethylazetidin-2-one as the sole reduced product, which was further converted to tosylate 54 using NaH/tosylimidazole. The debenzylation-oxirane formation sequence was conveniently performed as a single pot operation with ammonium formate, 5% Pd/C in refluxing methanol as the hydrogen transfer reagent combination. 

This study shows that by combining the diastereospecific reduction of acylaze-tidin-2-ones and the suitable functional group manipulations, it has been possible to synthesize the 3-spiro-epoxyazetidin-2-ones in a diastereospecific manner. 

Scheme 14 Stereospecific synthesis of 3-spiro-epoxyazetidin-2-ones...

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See also in sourсe #XX -- [ ]

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