We then turned to primary alcohols. Benzyl alcohol (3k) was also well tolerated under the reaction conditions to give 4ak in 78% and 93:7 er. However, when hexanol (3l) was submitted to the standard conditions, the desired product was obtained in good yield (84%), but lower selectivity (85:15 er). The use of a stoichiometric ratio between the Cu(I) salt and L1 afforded compound 4al in similar yield but higher enantioselectivity (93:7 er) (See SI, for more information). Ethanol (3m) afforded 4am in 85% yield and 93:7 er. The presence of a trimethylsilyl group (3n) was also well tolerated under the optimized conditions to give 4an in 58% yield and 90:10 er. This reaction was also performed at 1 mmol scale and product 4an was obtained in similar yield (51%) and a slightly higher selectivity (93:7 er). Switching to less nucleophilic alcohols, such as trifluoroethanol (3o), we observed poor selectivity and moderate yield. Scheme 2. Scope of the 3-CR with 2,2,2-trifluorodiazoethane (1) and different alcohols (3) and EBxs (2). a a The reactions were performed at 0.20 scale and isolated yield are given. The enantiomeric excess was obtained by chiral HPLC after flash column purification. The diastereomeric ratio was obtained from the crude reaction mixture by FNMR. b 2 mol% Cu(MeCN)4BF4 and 2 mol% L1.