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Convenient Syntheses of Fluorous Aryl Iodides and Hypervalent Iodine Compounds: ArI(L) n Reagents That Are Recoverable by Simple Liquid/Liquid Biphase Workups, and Applications in Oxidations of Hydroquinones
Author(s) -
Rocaboy Christian,
Gladysz John A.
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200390034
Subject(s) - chemistry , yield (engineering) , hypervalent molecule , reagent , toluene , aryl , medicinal chemistry , stereochemistry , nuclear chemistry , organic chemistry , alkyl , materials science , metallurgy
Iodinations of the ortho, meta , and para fluorous arenes (R f8 CH 2 CH 2 CH 2 ) 2 C 6 H 4 (R f8 =(CF 2 ) 7 CF 3 ) with I 2 /H 5 IO 6 in AcOH/H 2 SO 4 /H 2 O give 3,4‐(R f8 CH 2 CH 2 CH 2 ) 2 C 6 H 3 I ( 5 ) and the analogous 2,4‐ ( 6 ) and 2,5‐ ( 7 ) isomers, respectively. Spectroscopic yields are >90 %, but 5 and 7 must be separated by chromatography from by‐products (yields isolated: 70 %, 97 %, 61 %). Reaction of 1,3,5‐(R f8 CH 2 CH 2 CH 2 ) 3 C 6 H 3 with PhI(OAc) 2 /I 2 gives 2,4,6‐(R f8 CH 2 CH 2 CH 2 ) 3 C 6 H 2 I ( 8 ) on multigram scales in 97 % yield. The CF 3 C 6 F 11 /toluene partition coefficients of 5–8 (24 °C: 69.5:30.5 ( 5 ), 74.7:25.3 ( 6 ), 73.9:26.1 ( 7 ), 98.0:2.0 ( 8 )) are lower than those of the precursors, but CF 3 C 6 F 11 /MeOH gives higher values (97.0:3.0 ( 5 ), 98.6:1.4 ( 6 ), 98.0:2.0 ( 7 ), >99.3:<0.3 ( 8 )). Reactions of 5 – 8 with excess NaBO 3 in AcOH yield the corresponding ArI(OAc) 2 species 9 – 12 ( 9 , 85 % as a 90:10 9 / 5 mixture; 10 , 97 %; 11 , 95 %; 12 , 93 % as a 95:5 12 / 8 mixture). These rapidly oxidize 1,4‐hydroquinones in MeOH. Subsequent additions of CF 3 C 6 F 11 give liquid biphase systems. Solvent removal from the CF 3 C 6 F 11 phases gives 5 – 8 in >99–98 % yields, and solvent removal from the MeOH phases gives the quinone products, normally in >99–95 % yields. The recovered compounds 5 – 8 are easily reoxidized to 9 – 12 and used again.