Polycondensation, chemoselective

More elaborate chemoselective polycondensations have been reported since 2000. Ueda and coworkers tried direct polycondensation of 5-hydroxy or 5-aminoisophthalic acid and an aromatic diamine bearing a phenol moiety in the presence of DBOP (Scheme 24) [98]. The model reactions were first carried out to find the conditions for chemoselective polycondensation. The reaction of 5-hydroxyisophthalic acid with p-toluidinc in the presence of DBOP and triethylamine afforded the corresponding amide in a way similar to ordinary amidations with DBOP. On the other hand, the reaction of 5-aminoisophthalic acid with p-toluidine was dependent on the base used. When triethylamine, DBN, and DBU were used, a mixture of the desired... 

Furthermore, the chemoselective polyesterification of isophthalic acid with a bisphenol bearing amino group was investigated by direct polycondensation with DBOP and base (Scheme 25) [99]. Ueda and coworkers expected that phenolate was more nucleophilic than the aromatic amino group,... 

This method is especially useful when other acylation sensitive functional groups are present in the monomers, for example, polymers 11a, 11b, 11c were prepared with OH, NH2, COOH groups unprotected by this chemoselective polycondensation [16d] ... 

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