A high-yielding, asymmetric synthesis of novel 4-formyl-1-(2- and 3-haloalkyl)azetidin-2-ones was developed as valuable starting materials for the synthesis of different enantiomerically enriched bicyclic azetidin-2-ones, such as piperazine, morpholine, and 1,4-diazepane annulated beta-lactam derivatives. Especially the hydride reduction of 4-imidoyl-1-(2- and 3-haloalkyl)azetidin-2-ones turned out to be an efficient and straightforward method for the preparation 2-substituted piperazines and 1,4-diazepanes.
A new and efficient route to the biologically important title compounds is reported. -(VAN BRABANDT, W.; VANWALLEGHEM, M.; D'HOOGHE, M.; DE KIMPE*, N.; J.
Asymmetric Synthesis of 4-Formyl-1-(ω-haloalkyl)-β-lactams and Their Transformation to Functionalized Piperazines and 1,4-Diazepanes. -The chiral piperazine (III) and 1,4-diazepane annulated β-lactams (VII) are transformed into the novel compounds (V) and (VIII) via ring opening. The allylated β-lactams (IX) and (XII) do not afford the envisaged annulated β-lactams but furnish the unexpected synthetically interesting compounds (X) and (XIII) instead. The educts can be obtained via a slightly modified four-step literature procedure. -(DEKEUKELEIRE, S.; D'HOOGHE, M.; VANWALLEGHEM, M.; VAN BRABANDT, W.; DE KIMPE*, N.; Tetrahedron 68 (2012) 52, 10827-10834, http://dx.
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