Convenient syntheses of a family of easily recoverable fluorous primary, secondary, and tertiary aliphatic amines NH3-x[(CH2)(m)(CF2)(7)CF3](x) (m=3-5; x=1-3) - Fine tuning of basicities and fluorous phase affinities

The alcohols HOCH2(CH2)m(-1)(CF2)(7)CF3 [m = 3-5; (CF2)(7)CF3 = R-f8] are o xidized to aldehydes O=CH(CH2)(m-1)R-f8 (Dess-Martin reagent, 90-96%), whic h are condensed with NH2CH2C6H5 and Na(AcO)(3)BH to give benzylamines NH(CH 2C6H5)[(CH2)(m)R-f8 (excess amine, 88-90%)or N(CH2C6H5)[(CH2)(m)R-f8](2) (e xcess aldehyde, 85-91%). Subsequent hydrogenolyses (Pd/C, 1 atm H-2) give t he title primary amines NH2[(CH2)(m)R-f8] [10-12; 98-99%) or secondary amin es NH[(CH2)(m)R-f8](2) (13-15; 92-99%). The aldehyde condensations are repe ated with 13-15 to give tertiary amines N[(CH2)(m)R-f8](3) (16-18; 86-97%) with very high fluorous phase affinities. These decrease monotonically as t he numbers of CH2 groups increase or R-f8 groups decrease (CF3C6F11/toluene , 24 degrees C, 16/17/18/13/14/15/10/11/12: > 99.7:< 0.3,> 99.7:< 0.3, 99.5 :0.5, 96.5:3.5, 95.1:4.9, 93.0:7.0, 70.0:30.0, 63.2:36.8, 56.9:43.1). The r elative basicities towards CF3CO2H are probed by NMR in CDCl3. Competitions between N(CH2CH3)(3) or N[(CH2)(11)CH3](3) and 16-18 show 100% or < 95%, > 95% or 85-90%, and 85-90 or 65-70% protonation of the former. Competitions between 16/17, 17/18, and 16/18 show 60%, 85-90%, and > 95% protonation of the latter. Thus, an inductive effect of the R-f8 group is still detected through five CH2 groups.