Synthesis of activated esters

M Jaouadi, C Selve, JR Dormoy, B Castro, J Martinez. Isopropenyl chloroformate in the chemistry of amino acids and peptides. III. Synthesis of active esters of A-protected amino acids. Tetrahedron Lett 26, 1721, 1985. 

K Takeda, A Ayabe, M Suzuki, Y Konda, Y Harigaya. An improved method for the synthesis of active esters of A-protected amino acids and subsequent synthesis of dipeptides, (isopropenyl mixed carbonates) Synthesis 689, 1991. 

The occasional preliminary purification of products by aqueous washes usually coincides with the use of pyridine or dimethylformamide as solvent. Esters such as succinimido and benzotriazolyl are often prepared in situ, meaning that they are not isolated but subjected to aminolysis immediately after the esterification reaction.P " Slight decomposition can accompany the esterification of Boc amino acids, in particular if dichloromethane is used as solvent and the acidic EDC is used as reagent.P l Publications with a major focus on the synthesis of active esters using DCC are listed in Table 2. A list of Fmoc-Xaa-OR active esters that had been described to 1987 has been compiled.f l... 

Synthesis of Active Esters with Mixed Carbonates... 

Synthesis of Activated Esters. Haptens are frequently conjugated to carriers by means of activated esters. 

New methods for the synthesis of activated esters are a topic of continuous interest. The most recent of these was described during preparation of this text (361). 

H. Ogura, S. Nagai, and K. Takeda (1980), A novel reagent (A-succinimidyl diphenylphosphate) for the synthesis of activated ester and peptide. Tetrahedron Lett. 1467-1468. 

Diphthalimidocarbonate is a new reagent for the synthesis of active esters. A new photolabile support and a new technique for the hold-in-solution method provide improvements in the liquid-phase synthesis of peptides. The carboxy-group of an A -acylated amino-acid is protected by conversion into an oxazole ring photo-oxygenation regenerates the carboxy-group as a triamide, which is activated for peptide synthesis (Scheme 148). ... 

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