Solid-phase multi-step peptides

Carbo-2-(p-diphenyl)isopropoxy derivatives. N-2-(p-Diphenyl)isopropyloxycarbo-nylleucine stirred 1.5 hrs. at room temp, with acetic acid-formic acid-water (7 1 2) leucine. Y 94%. - Of a number of N-aralkoxycarbonyl protective groups tested 2-(p-diphenyl)isopropyloxycarbonyl was the most suitable for peptide syntheses (Helv. 51y 614). Selective and preferential removal in the presence of other acid-labile protective groups, especially those derived from rerr-butanol, also application in solid-phase multi-step syntheses, s. P. Sieber and B. Iselin, Helv. 51 y 622, 614 (1968). 

Hydrogen bromide acetic acid Solid phase multi-step syntheses Peptides... 

Peptides are not the only potential drug candidates. In most cases, other kinds of small organic molecules are preferred, because of their reduced susceptibility to enzymatic degradation. The split-mix method is fully applicable in the synthesis of organic libraries. Both sequential type and cyclic libraries can easily be prepared if the reaction conditions for solid phase are well developed. It has to be emphasized, however, that the advantages of the split-mix method can be fully exploited only in the case of multi-step synthetic procedures. For realization of the one-pot procedures suggested by Ugi [10], for example, the parallel procedures are better-suited. 

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