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. Author manuscript; available in PMC: 2022 Feb 23.
Published in final edited form as: Angew Chem Int Ed Engl. 2019 Feb 11;58(10):3198–3202. doi: 10.1002/anie.201900228

Table 2:

Catalyst optimization: Effect of an N-oxyl additive.[a]

graphic file with name nihms-1779912-t0005.jpg
Additive Yield [%] ee [%] Additive Yield [%] ee [%]
– 78 26 tBu2NO 63 60
TEMPO 60 21 2-Me-AZADO 71 57
4-oxo-TEMPO 50 29 AZADO 76 89
4-OAc-TEMPO 64 33 ABNO 90 91
4-OH-TEMPO 82 46 NO 39 54
[a]

Reaction conditions: 1 (0.2 mmol, 1 m), PhBr (4 m). Crude reaction mixtures were treated with aqueous NaOH to saponify the acetate. Yields determined by 1H NMR analysis using mesitylene as an internal standard; ee values determined by HPLC analysis on a chiral stationary phase.