Amide blocking group

The trivial name bisnorisopenicillin has been coined for the 6-acylamino-3-thia-l-a2abicyclo[3.2.0]heptane-2-carboxylic acid (85) structural class. While not extensively investigated, an example of this class has been prepared as shown in Scheme 66 (78JMC413). The following features of this sequence are noteworthy (a) the exclusively cis cycloaddition to form intermediate (86) and (b) the use of the 2,4-dimethoxybenzyl amide blocking group. 

When ACPC was condensed with hexamethylene diamine in the presence of two other acid chlorides (seb-acoyl or adipoyl chloride), poly(amide)s 6.6 and 6.10 with various numbers of azo groups per repeating unit (between 0.14 and 1.0, depending on the ratio of the acid chlorides used) could be obtained [35,36]. Thus, block copolymers with a controlled segment length of the poly-(amide) blocks were attainable. 

The protection of amino groups of amino sugars benefits particularly from the use of new blocking groups introduced for peptide synthesis. In this context, light-sensitive urethans and amides that can be utilized for the protection of amino groups in amino sugars are of particular interest in saccharide synthesis and modification. 

Here, the molar ellipticities are calculated per residue, which is the usual practice in peptide and protein work, and kn is the number of missing residues. For a peptide without blocking groups, the number of amides is one less than the number of residues, r=n — 1, and kr=kn — 1. If one terminus is blocked to form an additional amide, e.g. N-acylation or C-carboxyamidation, r and n are equal and so are kr and kn. If both termini are converted into amides, r=n +1 and kr=kn +1. 

The sulfonamide macrocycle proved to be a hospitable template, and at the same time the sulfonamide functionality bears the possibility of farther derivatiza-tion of [2]rotaxanes (see Section 8.4 Chemistry with Amide-Based Catenanes and Rotaxanes). Furthermore the expansion of the cavity did not afford a change of the blocking group - no disassembly of wheel and axle was detected. 

Figure 32. Porphyrin blocking groups offer the possibility of further supramolecular deri-vatization. Amide-linked rotaxane with porphyrin blocking groups 85, its Zn complex 86, and an unsymmetrically capped rotaxane 87.

Gly-Asn-Glu-Ala-Ser-Tyr-Pro-Leu-Glu-Hsl Assuming that the blocking group X is linked to the NH -terminal glycine by the usual amide bond, then hydrolysis should yield a carboxylic acid = 228. This corresponds to the of a C saturated fatty acid, the mass spectra are consistent with the supposition that X is C H CO-. This possibility was confirmed by... 

The rotaxane is composed of a glycylglycine chain, a simple dipeptide, bearing two diphenylmethane blocking groups, which prevent the dethreading of the benzylic amide macrocycle. The synthesis of the rotaxane structure is based on... 

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