Imidazole → 5-t-Butyldiphenylsilyloxy-4-(R)-iodopentanoic acid, methyl ester

Participants

Reaction Steps

To a solution of 7 (4.33 g, 11.2 mmol) in 250 mL toluene was added triphenylphosphine (5.9 g, 22.4 mmol), imidazole (2.3 g, 33.6 mmol), and iodine (4.26 g, 16.8 mmol) under a nitrogen atmosphere. The reaction mixture was lowered into a preheated heating mantle and refluxed for 1 hour. The reaction mixture was quenched by pouring into 200 mL saturated NaHCO3 solution. Excess triphenylphosphine was destroyed by the addition of iodine until an iodine coloration remained in the organic phase. The organic phase was then washed with 5% sodium thiosulfate solution (2×100 mL) and 2×200 mL water. The product was purified by flash chromatography with 6:1 hexane/ethyl acetate yield 4.75 g (85%) of a viscous oil; [α]D25 +6.5° (C=1, CHCl3); FAB MS 497 (M+H)+, 439 (M-t-butyl)+ ; 1H NMR (CDCl3) δ 7.89 (m, 4, ArH), 7.4 (m, 6, ArH), 4.15 (m, 1, H-4), 3.85 (m, 2, CH ), 3.7 (s, 3, OCH3), 2.5 (m, 2, CH2), 2.25 (m, 1, H-2), 2.1 (m, 1, H-2), 1.1 (s, 9, t-butyl).

Provenance & Evidence