Hydroxylation Hydroxy iodo benzene

With a-hydroxy ketones and their related tosyloxy derivatives. The imidazo [2,T ]thiazole 364 was prepared by acetic acid-catalyzed cyclocondensation of 2-hydroxy-l,2-diphenyl-ethanone with thiophenyl-substituted 2-aminothiazole 363 (Equation 163) <2002MI110>. Under MW irradiation and in the presence of montmorillonite K-10 clay, a mixture of a-tosyloxyketones 365 and 2-imidazolidinethione led to the substituted 5,6-dihydro-imidazo[2,l- ]thiazoles 366 (Equation 164) <1998J(P1)4093>. When using a-tosyloxyacetophenone, prepared by reaction of acetophenone with [hydroxyl(tosyloxy)iodo]benzene (HTIB), 5-aminopyrazole 367 could be converted to imidazo[l,2- ]pyrazole 368 in basic medium (Equation 165) <2005JHC209>. 

Hydroxylated 1,4-benzoquinones and 1,4-naphthoquinones gave similarly the corresponding dipoles [164]. The amino analogs reacted in the same way to afford first isolable iodonium salts and then the imino dipoles (Scheme 54) [165]. It is noted that the open-chain methyl 2-aminocrotonate gave with [hydroxy(tosyloxy)iodo]benzene only the iodonium salt, i.e. -MeC(NH2) = C(COOMe)I+Ph TsO- [166]. 

DMF, 1 atm. H2, 3 h) , and 1 1 ( H2, Pd/CaCOa, benzene r.t., 1 h) (Figure 4.44). Alternatively, for allylic alcohol derivatives steric blocking of the hydroxy group can be used to slow the reduction of the double bond. Thus with 152, the olefinic bond was reduced in competition with the aryl iodo substituent ( H2,10% Pd/C, Et20 or EtOH, 11-13 equiv. EtaN) even at short reaction times, but in 153 it was reduced only to the extent of 3% or less in reactions of 3 h duration, regardless of the substitution at the phenolic hydroxyl ". ... 

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