4-Toluenesulfonyl chloride → (+-)-2-Hydroxy-3-buten-1-yl tosylate

Participants

Reaction Steps

1,2-Dihydroxy-3-butene (20.00 g; 0.227 mol; 1.05 equiv) was dissolved in pyridine (200 mL). The reaction mixture was cooled in an ice bath and p-toluenesulfonyl chloride (p-TsCl) (41.11 g; 0.216 mol) was added in four portions over 30 min. After thorough mixing, the reaction mixture was placed at 4° C. for 18 h, at which time thin layer chromotography (hereinafter TLC) analysis indicated no p-TsCl. The mixture was concentrated to about half the original volume at reduced pressure from a 40° C. water bath and then diluted with ether (200 mL). The mixture was washed with water (100 mL), ice-cold 3N HCl until the washes remained acidic (2×100 mL), and saturated sodium bicarbonate (100 mL). After drying the organic solution (MgSO4), the solvent was removed to afford 41.73 g of a 91:9 mixture (1H nmr analysis) of the desired compound and the corresponding di-tosylate. The crude product solidified over several days at -20° C. It was recrystallized from methylene chloride (50 mL) by the addition of hexanes (100 mL) and chilling to -20° C. to afford two crops (total 33.33 g; 61%) of the desired compound which was pure by TLC analysis, mp 38°-44° C. 1H nmr (300 MHz, CDCl3): 7.800 (2H, d, J=8.25 Hz); 7.356 (2H, d, J=8.19 Hz); 5.751 (1H, ddd, J=5.38, 10.46, 16.55 Hz); 5.378 (1H, br d, J=17.05 Hz); 5.247 (1H, br d, J=10.48 Hz); 4.396 (1H, m); 4.066 (1H, dd, J=3.39, 10.20 Hz); 3.906 (1H, dd, J=7.41, 10.22 Hz); 2.451 (3H, s); 2.276 (1H, d, J=4.50 Hz). IR (KBr, cm-1): 3520 (s,b); 1650 (w); 1600 (s); 1350 (s); 1170 (s). Combustion Analysis: Theor--C, 54.53; H,5.82;N, 0. Found--C, 54.84; H, 5.86;N, <0.3.

Provenance & Evidence