反应详情

To a solution of 3-chloro-4-hydroxybenzaldehyde (4.21 g, 27 mmol) in degassed toluene (100 mL) is added ((4R)-2,2-dimethyl-[1,3]-dioxolan-4-yl)-methanol (5.35 g, 40.5 mmol), 1,1′-(azodicarbonyl)dipiperidide (13.63 g, 54 mmol) followed by tributylphosphine (10.93 g, 54 mmol). The mixture becomes slightly warm and a precipitate forms. The reaction mixture is diluted with degassed toluene (500 mL) and is stirred at it for 2 h, then at 60° C. for further 18 h before it is washed with 1 N aq. NaOH (3×150 mL) and water (150 mL). The organic phase is dried over MgSO4, filtered and concentrated to leave a dark brown oil which is chromatographed on silica gel eluting with hexane/EA 4:1 to give the title compound (4.30 g) as yellow oil. 1H NMR (CDC3): δ 9.82 (s, 1H), 7.89 (d, J=1.8 Hz, 1H), 7.74 (dd, J=1.8, 8.2 Hz, 1H), 7.05 (d, J=8.2 Hz, 1H), 4.56-4.43 (m, 1H), 4.23-4.17 (m, 2H), 4.14-4.08 (m, 1H), 4.06-4.00 (m, 1H), 1.47 (s, 3H), 1.41 (s, 3H).

1. temperatureThe mixture becomes slightly warm
2. washat 60° C. for further 18 h before it is washed with 1 N aq. NaOH (3×150 mL) and water (150 mL)
3. dry with materialThe organic phase is dried over MgSO4
4. filtrationfiltered
5. concentrationconcentrated
6. customto leave a dark brown oil which
7. customis chromatographed on silica gel eluting with hexane/EA 4:1