Mitsunobu synthesis of symmetrical alkyl and polyfluoroalkyl secondary amines

Trifluoromethanesulfonamides (triflamides) having the structure CF3SO2N[(CH2)3R]2 (R = CnF2n + 1 or CnH2n + 1, n = 4, 6, 8, 10) are obtained in high yields, when CF3SO2NH2 is reacted with 3-perfluoroalkyl-1-propanols or the parent aliphatic alcohols in a Mitsunobu reaction (Ph3P/[i-PrO2CNNCO2-i-Pr]/ether). Products are isolated easily by fluorous extraction, fluorous solid–organic liquid filtration or n-heptane/CH3OH extraction. Consecutive deprotection of triflamides with LiAlH4 in boiling ether or dioxane solution affords the title amines in good overall yields. Fluorous partition coefficients of the F-tagged amides and amines are determined and qualitatively analyzed.