Protecting group, phthalic anhydride

Another biocompatible and biodegradable polymer, chitosan, was converted into a multifunctional macroinitiator for the ZLL-NCA polymerization. Initially, the amine groups of chitosan were protected with phthalic anhydride, followed by triphenylmethyl protection of the 6-CH2OH groups. The amine groups were deprotected by hydrazine and used to... 

The statine-like moiety in one of the first drugs, saquinovir (23-8), comprises a transition state mimic for the cleavage of phenylalanylprolyl and tyrosylprolyl sequences. Constmction starts with the protection of the amino group of phenylalanine as its phthaloyl derivative (Phth) by reaction with phthalic anhydride this is then converted to acid chloride. The chain is then extended by one carbon using a Friedel-Crafts-like reaction. The required reagent (21-2) is prepared by reaction of the enolate obtained from the /7A-silyl ether (21-3) of glyoxylic acid and lithio... 

Phthalic anhydride, as protecting group, 104 Phthalimidoethyl bromide, alkylation with, 35... 

The phthalimlde group is typically introduced by reaction of a primary amine with phthalic anhydride in chloroform at 70 °C for 4 h (85-93% yield)1 or phthaloyl chloride in the presence of triethylamine [Scheme 8.10].20 2-Ch oro-carbonylbenzoic acid methyl ester in the presence of base [Scheme 8.11JT21-22 or N-ethoxycarbonylphthalimide23 have also been used with the latter reagent being especially useful for the -protection of a-amino acids [Scheme 8 12] m. 24... 

Functional group protections. Effective mediation by TaClj/SiOj is noted in the acetylation of alcohols and the formation of phthalimides from amines and phthalic anhydride, the latter process assisted by microwaves. The catalyst system is also useful for tetrahydropyranation of alcohols and dithioacetalizadon of aldehydes. ... 

Phthalyl alcohol, HOCH2CeH4CH20H-o. Mol. wt. 138.16, m.p. 64°. Prepared by reduction of phthalic anhydride with lithium aluminum hydride in ether (87% yield). In a novel and efficient synthesis of cyclopropanone hydrate, Grewe and Struve used the o-xylylene acetal protective group (1) and, after elimination of... 

A similar metal-coordination monomer can be prepared as outlined below [4]. In this case, the primary amino groups in diethylenetriamine are first protected as their phthalimides by heating in phthalic anhydride. The secondary amine is subsequently coupled to 4VBC in the presence of potassium carbonate in acetonitrile. After deprotection of the amines with hydrazine, the functional monomer is isolated, which can be further metallated with, e.g., Cu to yield a potent metal coordinating monomer. 

The benzidine rearrangement is also effective approach to the synthesis of unsymmetrical biaryls, if the starting material is uns5nnmetrically substituted A, A -diarylhydrazine, ArNHNHAr . In this manner, the reaction has been successfully used in the phenyl-heteroaryl series [85-87]. Namely, compound 510 underwent the benzidine rearrangement with four-molar excess of phthalic anhydride to the respective biaryl 511, whose amino groups are directly in situ protected as phthaloyl groups, in 75% overall yield, respectively. Scheme 44. 

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