1: 89 percent / MeONa / methanol / 24 h / 20 °C 2: 95 percent / N-ethylmorpholine; isobutyl chloroformate / tetrahydrofuran / 1 h / -5 - 20 °C 3: 82 percent / TsOH / methanol / 24 h / 20 °C 4: 86 percent / aq. HCl / 16 h / 20 °C View Scheme

1: 89 percent / MeONa / methanol / 24 h / 20 °C 2: 95 percent / N-ethylmorpholine; isobutyl chloroformate / tetrahydrofuran / 1 h / -5 - 20 °C 3: 82 percent / TsOH / methanol / 24 h / 20 °C 4: 86 percent / aq. HCl / 16 h / 20 °C View Scheme