390367-98-3Relevant articles and documents
Diazoketones as precursors in β-lactam synthesis. New insights into the mechanism of the photochemically induced Staudinger reaction
Linder,Frey,Podlech
, p. 2566 - 2577 (2001)
Diazoketones 1-3, derived from suitably protected amino acids (Ala, Val and Tle), have been photochemically rearranged in the presence of imines leading exclusively to trans-arranged 4-aryl- and cinnamoyl-substituted β-lactams 17-33 with up to 84% yield. Selectivities were dependent on the steric demand of the amino acid side-chain ranging from 65:35 to 90:10. The relative configurations were proved by several X-ray crystal structures and comparison of NMR spectra. Further reactions of the azetidinones at position C-4 have been performed: electron-rich aryl substituents (e.g., 4-methoxyphenyl, furyl and thienyl) could be degraded to carboxylic acids 34 and 35 which were further transformed to acetoxy derivatives (compounds 36 and 37) in a Kolbe reaction of type II. The cinnamoyl group could be oxidized to the formyl group by ozonolysis (→38,39). The mechanism of the photochemically induced β-lactam formation is discussed in detail.
