Fig. 3. Late-stage alkylations.

Reaction conditions: ^aHemiaminal 2 (0.1 mmol), CH₂Cl₂ (1.0 mL), DAST (0.1 mmol) added at −78 °C; rt for 1 h; cooled to −78 °C, AlMe₃ (0.3 mmol) added, stirred 2 h; rt for 1 h, yield of the second step. ^b1l or 1y (0.2 mmol), H₂O (0.3 mmol), CuOAc (0.02 mmol), L2 or L1 (0.022 mmol), NFSI (0.3 mmol), CH₃CN (2.0 ml), under N₂, followed by CH₂Cl₂ (1.0 mL), DAST (0.1 mmol) at −78 °C; rt for 1 h; cooled to −78 °C, AlMe₃ (0.3 mmol) added, stirred 2 h; rt for 1 h, overall yield of two steps. ^cHemiaminal 2 (0.1 mmol), CH₂Cl₂ (1.0 mL), DAST (0.1 mmol) added at −78 °C; rt for 1 h; cooled to −78 °C, RMgBr (0.4 mmol) added, stirred for 5 h; rt for 1 h. ^d(A) bpy (0.4 mmol), THF (0.5 mL), RMgBr (0.4 mmol) added at −40 °C for 0.5 h; rt for 0.5 h; (B) 1l (0.1 mmol), CH₂Cl₂ (1.0 mL), DAST (0.1 mmol) added at −78 °C; rt for 1 h; (B) added to (A), stirred 5 h at −40 °C; rt for 1 h. ^e(A) CuBr·Me₂S (0.4 mmol), THF (0.5 mL), RMgBr (0.4 mmol) added at −40 °C for 0.5 h; rt for 0.5 h; (B) 1a (0.1 mmol), CH₂Cl₂ (1.0 mL), DAST (0.1 mmol) added at −78 °C; rt for 1 h; (B) added to (A), stirred for 5 h at −40 °C; rt for 1 h. ^f1a (1.0 mmol), TFA (2.0 mL), NaBD₄ (4.0 mmol) added at 0 °C; rt for 2 h.