Trityl, protecting group

It has been shown that glyeine amides of aminobenzophenones are readily converted to the corresponding benzodiazepines in vivo. Peptides which terminate in such a moiety should thus serve as a benzodiazepine prodrug after hydrolysis by peptidases. One of the glycine residues in lorzafone (194)is presumably removed metabolicaUy in this manner to give a benzodiazepine precursor which spontaneously cyclizes. Acylation of benzophenone 190 with the trityl protected dipeptide 191, as its acid chloride 192, affords the amide 193. Removal of the trityl protecting group with acid yields lorzafone (194) [50]. 

In subsequent studies,22 Sheehan et al. demonstrated that the action of diisopropylcarbodiimide on penicilloate 24, prepared by protection of the free primary amino group in 23 with trityl chloride (see Scheme 6b), results in the formation of the desired -lactam 25 in a very respectable yield of 67 %. In this most successful transformation, the competing azlactonization reaction is prevented by the use of a trityl group (Ph3C) to protect the C-6 amino function. Hydrogenolysis of the benzyl ester function in 25, followed by removal of the trityl protecting group with dilute aqueous HC1, furnishes 6-aminopenicillanic acid (26), a versatile intermediate for the synthesis of natural and unnatural penicillins. 

Remove the trityl-protecting group by dissolving the derivatized fulleropyrrolidine in 5 ml of dichloromethane in a fume hood and then adding 50 pi of TFMSA (caution ) with stirring. 

React at room temperature for 1 hour to remove the trityl-protecting group, yielding the N-H pyrrolidine derivative of C60-... 

The trityl protecting group is readily removed under Birch conditions. ... 

In the second procedure13 (see Scheme 3), D-glucitol (10) was converted into 5-O-benzoyl-1,3 2,4-di-O-ethyl idene-6-O-trityl-D-glucitol (17) by successive treatment with acetaldehyde to produce 15, with chlorotriphenylmethane to provide 16, and with benzoyl chloride to afford 17. Selective removal of the trityl protecting group from 17, to give 18, followed by oxidation of 18, provided 19 which, on hydrolysis, afforded L-gulose (9). 

The trityl-protecting group was removed by treatment of the 480 teabags with 2% TFA in DCM (twice for 10 min). 

Benzylation of l,6,6 -tri-0-tritylsucrose afforded the fully protected derivative from which the trityl protecting groups were removed under controlled acidic... 

A completely different approach to the total synthesis of enterobaetin has been reported by Shanzer and Libman 100>. This is based on a single-step conversion of the tritylated serine-lactone to the cyclic triester enterobaetin backbone via the use of a cyclic organotin compound as template. This is followed by subsequent replacement of the trityl protecting groups by catechol residues to yield enterobaetin. 

With 2 -deoxyribopurines, the lability of the glycosyl linkage to the acidic conditions generally required for detritylation precludes the use of the trityl protecting group in the synthesis of 2 -deoxynucleotides. 3, 5 -Di-... 

Figure 8.3 Process of solid-phase phosphoramidite nucleotide synthesis. In the process, X = linker which is later incorporated into the polymer matrix DMTr = dimethoxy trityl protecting group which is removed by treatment with add to hberate the hydroxyl gronp for snbseqnent phosphitylation reaction. B s = protected purine and pyrimidine bases. Phosphite is oxidized with iodine in the presence of esterification agent to phosphotriester before the chain extension or it is oxidized at the completion of chain extension as shown...

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