Convenient Modular Syntheses of Fluorous Secondary Phosphines and Selected Derivatives

Reactions of the fluorous primary phosphines R fn (CH 2 ) 2 PH 2 [R fn =(CF 2 ) n−1 CF 3 ; n=6, 8, 10] and R fn′ CHCH 2 [(n′=6, 8, 10) (1 : 1; THF, reflux) in the presence of AIBN give the title compounds [R fn (CH 2 ) 2 ][R fn′ (CH 2 ) 2 ]PH [n/n′=6/6 ( 4 , 55%), 8/8 ( 5 , 58%), 10/10 ( 6 , 53%), 8/6 ( 7 , 52%), 10/8 ( 8 , 51%)] as low‐melting white solids on up to 10‐g scales. The chiral tertiary phosphine [R f6 (CH 2 ) 2 ][R f8 (CH 2 ) 2 ][R f10 (CH 2 ) 2 ]P ( 9 ) is similarly prepared from 7 and R f10 CHCH 2 in the presence of VAZO (neat, 100 °C; 67%). The reaction of 5 and THF⋅BH 3 yields the phosphine borane 5 ⋅BH 3 (95%). Additions of triphosgene [(CCl 3 O) 2 CO] to 5 or R f8 (CH 2 ) 2 PH 2 give [R f8 (CH 2 ) 2 ] 2 PCl or R f8 (CH 2 ) 2 PCl 2 , which are characterized in situ. The CF 3 C 6 F 11 /toluene partition coefficients of 4 – 9 increase with the number and lengths of the R fn segments.