The synthesis of optically pure β-lactams derived from sugars. High-pressure [2+2] cycloaddition of toluene-4-sulphonyl isocyanate to glycals.

[2+2] Cycloaddition of toluene-4-sulphonyl isocyanate to glycals 1 - 4 at room temperature under 10 kbar pressure gave respective β-lactams 5 - 8 in good yields. The reaction proceeds regio- and stereospecifically to afford the four-membered ring in position trans to the acetoxy group at C-3 of the glycal moiety.