Convenient Syntheses of Fluorous Phenols of the Formula HOC6H5-n((CH2)3 (CF2)7CF3)n (n = 1,2) and the Corresponding Triarylphosphites

Autor: Ralf Meier, Sylvie Le Stang, Christian Rocaboy, John A. Gladysz
Rok vydání: 2003
Předmět:
Zdroj: ChemInform. 34
ISSN: 1522-2667
0931-7597
DOI: 10.1002/chin.200320191
Popis: 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 [Ph3PCH2CH2Rf8]+I− (Rf8=(CF2)7CF3) to give PhCH2OC6H4CHCHCH2Rf8 (86–93%, Z major). Reactions with H2 over Pd/C give the fluorous phenols HOC6H4(CH2)3Rf8 (4a,b; 87–91%). Condensations with PCl3 and NEt3 (3.0:1.0:3.3 mol ratio) give the fluorous phosphites P[OC6H4(CH2)3Rf8]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)3Rf8)2 (11c; 97%/96%, two steps) and phosphite P[OC6H3((CH2)3Rf8)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).
Databáze: OpenAIRE
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