摘要:
The aldehydic benzyl ethers PhCH2OC6H4CHO (2; a/b = para/meta series) are readily available from the corresponding phenols and react with Wittig reagents derived from LPh3PCH2CH2Rf8]I-+(-) (R-f8 = (CF2)(7)CF3) to give PhCH2OC6H4CH=CHCH2Rf8 (86-93%, Z major). Reactions with H-2 over Pd/C give the fluorous phenols HOC6H4(CH2)(3)R-f8 (4a,b; 87-91%). Condensations with PCl3 and NEt3 (3.0:1.0:3.3 mol ratio) give the fluorous phosphites P[OC6H4(CH2)(3)R-f8](3) (5a,b; 92-94%), but traces of 4a,b are difficult to remove. The phthalate-based benzyl ethers PhCH2OC6H3 (COOR)(2) (7; c/d = 3,5/3,4 -OC6H3-3,n-(R)(2) series) are easily accessed and reduced with LiAlH4 to the diols PhCH2OC6H3(CH2OH)(2) (8c,d; 89-90%). Diol 8c and the Dess-Martin periodinane react to give the dialdehyde PhCH2OC6H3(CHO)(2) (9C; 95%). This is elaborated by a sequence analogous to 2 --> 4 --> 5 to the fluorous phenol HOC6H3((CH2)(3)R-f8)(2) (11C; 97%/96%, two steps) and phosphite P[OC6H3((CH2)(3)R-f8)(2)](3) (12c, 92%), from which traces of 11c are difficult to remove. Diol 8d can be similarly elaborated to 11d, but the dialdehyde 9d is labile and the combined yield of the Dess-Martin[Wittig steps is 32%. The CF3C6F11/toluene partition coefficients of 11c,d, and 12c (two pony tails; 70:30, 72:28, 92:8) are much higher than those of 4a and b (one pony tail; 12:88, 14:86). (C) 2002 Elsevier Science B.V.. All rights reserved.