SYNTHESIS OF 1-OXABICYCLIC β-LACTAM PRECURSORS FROM 4,6-O-BENZYLIDENE-D-ALLAL
Cycloaddition of trichloroacetyl isocyanate to 4,6-O-benzylidene-D-allal 4 followed by N-deprotection of the adduct produces β-lactam 9 with a good yield.Subsequent N-benzylation, 4,6-O-deprotection by hydrogenolysis, and a glycolic cleavage of the vic di