1: 29.5 percent / NaBH4, tributyltin chloride / methanol / Irradiation 2: 96.2 percent / NaBH4, boron trifluoride etherate / tetrahydrofuran / 2 h / Ambient temperature View Scheme

Multi-step reaction with 2 steps 1: triethylamine / dimethylformamide / 0.33 h / -10 - -5 °C2: triethylamine / dimethylformamide / 24 h