Fig. 4: Substrate scope of α-diazo esters.

Unless otherwise noted, the reactions were carried out with helical fluorenone A1 (0.05 mmol), diazo compound B (1.25 equiv.), Sc(OTf)3/NO-3 (1.3:1, 10 mol%) in 1,1,2,2-TCE (0.025 M) under air atmosphere. Isolated yields after column chromatography separation. The d.r. value was determined by 1H NMR spectroscopy and the e.e. was determined by HPLC.