(3-Carboxypropyl)(triphenyl)phosphanium bromide → 3-Fluoro-2-methoxybenzoic acid

Participants

Reaction Conditions

Reaction Steps

Solid potassium t-butoxide (4.48 g) was added under argon to a stirred, ice-cooled mixture of (3-carboxypropyl)triphenylphosphonium bromide (6.44 g) and (-)-[2,3-trans]-tetrahydro-5-hydroxy-3-hydroxymethyl-2-o-methoxyphenylfuran (B) (2.24 g) ih dry THF (75 ml). The mixture was stirred for 15 minutes at 4° C., then for 1 hour at ambient temperature and was then poured into ice-water (150 ml). The mixture obtained was washed with ether (2×50 ml) to remove the bulk of the neutral material. The aqueous phase was acidified to pH4 with 1M hydrochloric acid and extracted with ether (1×100 ml, 2×50 ml). These combined extracts were washed successively with water (2×50 ml) and saturated brine (2×50 ml), then dried (MgSO4) and evaporated. The residue was purified by flash chromatography, eluting with ether/hexane/acetic acid (80:20:1 v/v) to give (-)-erythro-4(Z)-8-hydroxy-7 -hydroxymethyl-8-o-methoxyphenyl-4-octenoic acid (C) as a colourless oil (2.76 g); 22 [α]D -68.3° (c 1.1, methanol); NMR: 1.92 (1H,m), 2.0-2.6 (6H,m), 3.67 (2H,m), 3.82 (3H,s), 5.21 (1H,d J=5 Hz), 5.37 (2H,m), 6.87 (1H,dd J=8,1 Hz), 6.98 (1H,td J=7,1 Hz), 7.25 (1H,m), 7.42 (1H,dd J=7,1 Hz); m/e 294 (M+).

Provenance & Evidence