Water-soluble derivatives of furylphosphanes

(2-Furyl)diphenylphosphane (1), bis(2-furyl)phenylphoslphane (8) and tris(2 -furyl)phosphane (9) have been converted into their water soluble 5-carboxy lates 4, 11 and 12, 5-phosphonates 14 and 16 and 5-sulfinates 17-19. In mos t cases, the selected route involved a 5-bromo to 5-lithio exchange reactio n, followed by reaction with CO2, ClP(O)(OEt)(2) or SO2. The furan group sh arply enhances the water-solubility of these products when compared with th e corresponding benzene derivatives. Catalytic tests in hydrogenation, hydr oformylation and Heck cross-coupling reactions showed that the sulfinate gr oup tends to inhibit the catalysis and, in addition, a sharp drop in activi ty was observed with the trifunctional products 12 and 19. Overall, the pho sphonates 14 and 16 appear to be the most promising ligands for biphasic ca talysis.