2-Substituted azetidines, asymmetric synthesis

In 2002, the asymmetric synthesis of 3-substituted 3-hydroxy-p-lactams has been reported to be realized by metal-mediated l,3-butadien-2-ylation reactions between 1,4-dibromo-2-butyne and optically pure azetidine-2,3-diones [64]. This latter starting material was prepared via Staudinger reaction followed by sequential transesterification and Swem oxidation (Scheme 15), [65]. 

The glycol-cleavage oxidation has been utilized in numerous synthetic works, for example, the total syntheses of dipiperidine alkaloids virgidivarine and virgiboidine [1348], total synthesis ofresolvinE2 [1349], synthesis of a-substituted oxazolochlorin aminals or acetals from mera-tetraaryldihydroxychlorins [1350], asymmetric synthesis of l-(2- and 3-haloalkyl)azetidin-2-ones [1351], synthesis of 2-hydroxy-1,4-oxazin-... 

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