Water → 2-Bromo-5-(1,3-dioxan-2-yl)pyridine

Participants

Reaction Steps

To a solution of 6-bromopyridine-3-carbaldehyde (7) (25 g, 134 mmol) in toluene (130 mL) were added 1,3-propanediol (27) (20.45 g, 269 mmol) and 10-camphorsulfonic acid (3.12 g, 13.44 mmol). The reaction mixture was heated to reflux, with azeotropic removal of the evolved water, for 50 minutes, cooled down to r.t. and concentrated. The residue was partitioned between EtOAc (150 mL) and saturated aqueous NaHCO3 solution (100 mL). Organic phase was collected and the aqueous phase was extracted with EtOAc (2×150 mL). Combined organic fractions were washed with brine (100 mL), dried over Na2SO4, filtered and concentrated to yield a brown solid which was triturated with Et2O and hexane (10/200 mL), to afford intermediate 28 (27.7 g, 84% yield) as a beige solid. MS (m/z): 244.1, 246.1 (M+H). 1H NMR (400 MHz, DMSO-d6) δ (ppm): 8.40 (d, J=2.4 Hz, 1H), 7.35 (dd, J=8.0, 2.4 Hz, 1H), 7.66 (dd, J=8.0, 0.4 Hz, 1H), 5.61 (s, 1H), 4.15 (ddd, J=11.8, 5.0, 1.2 Hz, 2H), 3.98-3.91 (m, 2H), 2.028-1.95 (m, 1H), 1.46 (d quint, J=13.2, 1.2 Hz, 1H).

Provenance & Evidence