Tert-Butyldimethylsilyl-protected

Method B In contrast, reprotonation of the tert-butyldimethylsilyl-protected nitronate anions gives awh-isomers selectively (41 9-19 1). 

Nevertheless, the direct nucleophilic displacement of support-bound carboxylates to prepare hydroxamates presents some limitations. For example, O-tert-butyldimethylsilyl-protected hydroxylamine displaces common acids from oxime resin however, further treatment with trifluoroacetic acid (TFA) is necessary to remove completely the silyl... 

Table 16 O-Trimethylsilyl-, 0-[2-(Trimethylsilyl)ethyl]-, and O-tert-Butyldimethylsilyl-Protected Tyrosine...

Oxazolidine 144 obtained from amino alcohol 143 and ethyl trifluoropyruvate is also a synthetic intermediate for 2-amino-2-trifluoromethylpentanoic acid 145. Lewis acid-catalyzed allylation of 144 with allyl silane occurs in excellent yield with a moderate stereoselectivity. Meanwhile, O-tert-butyldimethylsilyl-protected imine 146 gives better diastereoselectivity although yield is poor (see Scheme 9.31) [57]. 

PCTFE poly(chlorotrifluoroethylene) TBDMS tert-butyldimethylsilyl protecting... 

The synthesis of a nucleotide-like phosphoramidite building block in which the nucleic base has been replaced by a tert-butyldimethylsilyl-protected styrene glycol (47) has been described. After its incorporation in an oligonucleotide by automated synthesis, the terminal alcohol has been oxidized with NaI04 after fluoride deprotection. A similar phosphoramidate in which the nucleic base has been replaced by an alkyl diol (48) has been incorporated in an oligonucleotide and further conjugated with biotin after oxidation to the aldehydic functional-ity. ... 

A study of the mechanism of the addition of trimethylsilyl cyanide to epoxide 10 is consistent with the generation of a carbenium ion31 (equation 24). The structure of the principal product 11 was confirmed by an X-ray crystal structure. Terf-butyldimethylsilyl cyanide opens epoxides to give the tert-butyldimethylsilyl protected 0-hydroxy isocyanides32 (equation 24a). 

The first application of this methodology was directed to the preparation of phenol-terminated polymers. The tert-butyldimethylsilyl-protecting group was chosen for the aromatic hydroxyl group based on the results reported by Nakahama and co-workers. PSLis (Aln= 1-5x10 - 13.1 X lO gmoD ) were functionalized with l-(4-tgrt-butyl-dimethylsiloxyphenyl)-l-phenylethylene (23, 0.2 molar... 

Cyclic carbonate chemistry has also proven to be useful for the preparation of branched or cross-linked polymers. First branched (hyperbranched) PCs were synthesized by Bolton and Wooley. In one of the published methods of synthesis of hyperbranched PCs they used chloroformate-type l,l,l-tris(4-hydroxyphenyl) ethane (THPE)-based monomers (Scheme 100). The authors synthesized hyperbranched aromatic PCs by the polymerization of A2B and AB2 monomers, which involved the condensation of chloroformate (Scheme 104) functionalities with tert-butyldimethylsilyl-protected phenols (Scheme 104), facilitated by reactions with silver fluoride. 

The silyl groups at the newly formed benzene ring were cleaved by the action of acetyl chloride in anhydrous methanol and tetrabutylammonium fluoride to yield 34 and 35, respectively. A Tamao-Fleming-like oxidation to furnish the respective phenol derivatives did not take place, probably due to the sp -hybridized carbon of the arene moiety. To install the anthraquinone moiety by oxidation of the benzylic positions, it was necessary to reprotect the alcohol functionalities. After tert-butyldimethylsilyl protection of the hydroxyl moieties to afford 36, an iron(III)-catalyzed benzylic oxidation proceeded smoothly with yields up to 70%. Finally, hydrolysis with hydrochloric acid of the protecting groups generated the desired anthracycline derivatives 38 based on a carbohydrate skeleton [21,22] (Scheme 8.8). 

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