Design and synthesis of new ¯uorinated ligands for the rhodium-catalyzed hydroformylation of alkenes in supercritical CO 2 and ¯uorous solvents Dominique Bonafoux, Zihao Hua, Beihan Wang, Iwao Ojima * Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA Abstract Novel ¯uorous biphenols, 5,5 0 -[n-C 4 F 9 CH 2 ) 3 ] 2 -2,2 0 -biphenol and 5,5 0 -[n-C 4 F 9 CH 2 ) 3 O] 2 -3,3 0 -di-tert-butyl-2,2 0 -biphenol, as well as enantiopure BINOLs, S)-6,6 0 -[n-C 4 F 9 CH 2 ) 3 ] 2 -BINOL, R)-6,6 0 -[n-C 6 F 13 CH 2 ) 3 ] 2 -BINOL, and S)-6,6 0 -[n-C 8 F 17 CH 2 ) 3 ] 2 -BINOL, are synthesized. These compounds serve as key intermediates for the syntheses of a variety of new ¯uorous ligands for regioselective and enantioselective catalytic reactions. Novel ¯uorous [RfCH 2 ) 3 ] 2 -BINAPHOS ligands Rf  n-C 4 F 9 , n-C 6 F 13 , and n-C 8 F 17 ) are successfully synthesized. These new ¯uorous chiral ligands when used with a rhodium catalyst can achieve comparable or even higher regioselectivity and enantioselectivity in the asymmetric hydroformylation of styrene as compared to those by the Rh-BINAPHOS system. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Fluorous ligands; Fluorous BINOL; Fluorous BINAPHOS; Fluorous biphenol; Catalytic asymmetric synthesis; Enantioselective; Hydroformyla- tion; Phosphine±phosphite; Diphosphite 1. Introduction Transition metal-catalyzed hydrocarbonylation reaction of unsaturated hydrocarbons is one of the most powerful methods for the syntheses of aldehydes, alcohols, esters and carboxylic acids. The most widely used and commercially important process among these reactions is the hydroformy- lation of ole®ns [1,2]. The use of supercritical ¯uids, in particular scCO 2 as environmentally friendly reaction med- ium in place of conventional organic solvents has recently attracted signi®cant interest [3±8]. On the other hand, the ¯uorous biphase catalysis introduced by Horva Âth and Ra Âbai [9±11] provides a new and practical concept for the recovery and recycling of the expensive catalysts used in these transformations. In order to transpose the hydroformylation reaction to scCO 2 and/or ¯uorous phase, the catalyst system must be soluble in scCO 2 or preferentially soluble in ¯uor- ous solvents over conventional organic solvents. This can be achieved by modifying known ligands with `solubilizing' per¯uoroalkyl tails to increase the af®nity of the ligands to scCO 2 or ¯uorous solvents. Accordingly, we started the design and syntheses of new diphosphite and chiral phos- phine±phosphite ligands with per¯uoroalkyl tails. The for- mer ligands are the congeners of BIPHEPHOS [12±14] that is an excellent ligand for highly linear-selective hydrofor- mylation of 1-alkenes and the latter ligands are the analogs of BINAPHOS [15,16] that is the best chiral ligand to date for the asymmetric hydroformylation of vinylarenes. While our research was in progress, Francio Á and Leitner [7] reported their synthesis of a ¯uorous R,S)-BINAPHOS bearing a 2-per¯uorohexyl)ethyl group at the meta-position of diphenylphosphinyl moiety, and its successful application to the Rh-catalyzed asymmetric hydroformylation of viny- larenes in scCO 2 . Our design of ¯uorous BINAPHOS ligands is different from that of Francio Á and Leitner in that per¯uoroalkyl tails are attached to the peripheral naphthyl moieties, and the same approach is taken for designing ¯uorous BIPHEPHOS ligands Fig. 1). Another important feature of our approach is to make a small library of ¯uorous ligands using biphenols as well as enantiopure binaphthols BINOLs) bearing 3-per¯uoroalkyl)propyl tails as key common units. It should be noted that those enantiopure BINOLs bearing 3-per¯uoroalkyl)propyl tails can be applied to a variety of BINOL-based asymmetric transfor- mations and also be converted to ¯uorous BINAP, MOP, BIPHENPHOS, etc. in addition to ¯uorous BINAPHOS. We report here our approaches towards the syntheses of [n-C 4 F 9 CH 2 ) 3 ] 4 -BIPHEPHOS 1a), [n-C 4 F 9 CH 2 ) 3 O] 2 - BIPHEPHOS 1b) and the successful syntheses of R,S)- Journal of Fluorine Chemistry 112 2001) 101±108 * Corresponding author. Tel.: 1-631-632-7947; fax: 1-631-632-7942. E-mail address: iojima@notes.cc.sunysb.edu I. Ojima). 0022-1139/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII:S0022-113901)00473-0