13165-89-4Relevant articles and documents
An Oxidative Rearrangement of t-Butyl (3RS,5SR)-2-Ethoxycarbonylcarbapen-1-em-3-carboxylate to t-Butyl (1RS,5SR,7RS,8SR)-8-Ethoxycarbonyl-8-hydroxy-3-oxo-2-oxa-6-azabicyclooctane-7-carboxylate
Beagley, Brian,Larsen, David S.,Pritchard, Robin G.,Stoodley, Richard J.,Whiting, Andrew
, p. 1127 - 1137 (2007/10/02)
The title reaction (10a)> is induced by the action of osmium(VIII) oxide.Presumably, the diol (12), formed by the addition of the elements of hydrogen peroxide to the endo-face of the 1,2-double bond of the precursor (1a), is an intermediate in the reorganisation.The rearrangement product is shown to possess structure (10a) by X-ray crystallography.Compound (10a) undergoes dehydrogenation in the presence of lead(IV) acetate or chromium(VI) oxide to give t-butyl (1RS,5SR,8SR)-8-ethoxycarbonyl-8-hydroxy-3-oxo-2-oxa-6-azabicyclooct-6-ene-7-carboxylate (13a).Unusual results are encountered when compound (10a) is subjected to methylsulphonylation conditions.Thus, with methanesulphonyl chloride and triethylamine in dichloromethane, it reacts to give the O-methanesulphonate (10d) as the major product and (depending upon the experimental conditions) either the N-methylsulphonylmethylsulphonyl-O-methylsulphonyl derivative (10f) or the N-methylsulphonylmethylsulphonyl derivative (10h).The last-cited compound is the major product when the oxazabicyclo-octane (10a) is added to an 'aged' mixture of methanesulphonyl chloride and triethylamine in acetonitrile.In the presence of methanesulphonyl chloride in pyridine, compound (10a) is transformed into the N-methylsulphonyl derivative (10c).A study of the 300 MHz 1H n.m.r. spectra of oxazabicyclo-octanes of type (10) and oxazabicyclo-octenes of type (13) reveals some unexpected downfield shifts of the 1-hydrogen atoms as a consequence of O-substitution.
