Deprotection acid-catalyzed, poly

Since only Ta and Nb catalysts, which are not tolerant to polar groups, are available for the polymerization of disubstituted acetylenes, it is generally difficult to synthesize disubstituted acetylene polymers having such a highly polar substituent as a hydroxy group. Recently, synthesis of poly[l-phenyl-2-( -hydroxyphenyl)acetylene] has been achieved by the polymerization of 1-phenyl-2-(p-siloxyphenyl)acetylene and the subsequent acid-catalyzed deprotection reaction. 

SCHEME 12.3 Acid catalyzed deprotection of a poly(r T-butoxycarbonyloxy styrene) PTBOCST resists by the strong Bronsted acid formed in the prior photolysis reaction of a PAG. 

Scheme 7.33 Acid-catalyzed deprotection of poly(4-hydroxystyrene-co-4-polyhydroxy-styrene-tert-butyl ester).

Poly(methyl methacrylate)-hased resists comprise a significant fraction of positive resists used in 193-nm and 157-nm lithographies. These resists are largely based on the acid-catalyzed deprotection of tertiary ester groups. 

Direct alkylation of hydrazine itself with halides and sulfates usually gives mixtures of mono- and poly-alkylated hydrazines. It is possible to get useful yields of the monoalkylhydrazine by using an excess of hydrazine. Several specific procedures leading to monoalkylhydrazines are based on selective alkylation of hydrazine derivatives with protecting groups attached. So, easily prepared acetone N-(diethoxyphosphoryl)hydrazone (75) can be used. Phase-transfer catalyzed N-alkylation of (75), followed by deprotection with p-toluenesulfonic acid provides monoalkylhydrazine sulfonates (76 Scheme 17). Similarly, N-alkyl-N-arylhydrazines have been prepared by phase-transfer catalyzed N-alkylation of arylhydrazones (Scheme 18). An efficient, one-pot method for the synthesis of a variety of polysilyl-ated hydrazines employs hexamethyldisilane (equation 30). Polysilylated hydrazines were found to react with aldehydes or ketones to give hydrazones under anhydrous conditions. By treatment with triphenylphosphine and diethyl azodicarboxylate primary and secondary alcohols can be converted to hy-dr ine derivatives (equation 31). ... 

The azide-alkyne click reactions are useful to attach a number of polar FGs including various azobenzene moieties to the pendants of poly(l-phenyl-5-chloro-l-pentyne), (Eq. (7)) [90]. Nucleophilic substitutions of the same starting polymer result in the formation of an imidazole-functionalized, disubstituted acetylene polymer, (Eq. (8)) [91]. The degree of incorporation of the imidazole moiety is about 65%, and the product polymer exhibits good solubility in ethanol. Hydrolysis reaction of poly[l-(/w-methoxycarbonylphenyl)-l-octyne] yields a carboxy-functionalized disubstituted acetylene polymer poly[l-(/w-carboxyphenyl)-l-octyne], (Eq. 9) [92]. Hydrazine-catalyzed deprotection of poly[l-phenyl-ll-Af-benzimide-l-undecyne] affords the corresponding polyamine, which can be further ionized with hydrobromic acid to give a polyelectrolyte ammonium salt, (Eq. (10)) [93]. 

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