149207-52-3Relevant articles and documents
Synthesis of a new molecular carrier: N-(Leu-enkephalin)yl 6-amido-6-deoxy-cyclomaltoheptaose
Djedaini-Pilard, Florence,Desalos, Jacques,Perly, Bruno
, p. 2457 - 2460 (1993)
The synthesis of N-(Leu-enkephalin)yl 6-amido-6-deoxy-cyclomaltoheptaose has been performed in high yield. The final derivative has been characterized by proton NMR in terms of chemical and inclusion properties and represents a new class of target-directed transporters.
Thiophene backbone amide linkers, a new class of easily prepared and highly acid-labile linkers for solid-phase synthesis
Jessing, Mikkel,Brandt, Malene,Jensen, Knud J.,Christensen, Jorn B.,Boas, Ulrik
, p. 6734 - 6741 (2007/10/03)
Solid-phase synthesis is of tremendous importance for small-molecule and biopolymer synthesis. Linkers (handles) that release amide-containing products after completion of solid-phase synthesis are widely used. Here we present a new class of highly acid-labile backbone amide linkers (BAL handles) based on 3,4-ethylenedioxythiophene (EDOT), which we have termed T-BAL. These thiophene linkers are synthesized in three convenient steps from commercially available EDOT. In the linker design, the spacer was introduced to the EDOT core either via a carbon-carbon bond or via a thioether linkage. Introduction of the spacer via a C-C bond was performed by a chemoselective Negishi coupling without transient protection of the aldehyde group to provide the T-BAL1 handle. Introduction via a thioether linkage was performed by a facile nucleophilic aromatic substitution between the brominated EDOT aldehyde and unprotected mercapto acids to provide T-BAL2 and T-BAL3 handles. The minimal use of protecting groups gave the corresponding linker molecules in few synthetic steps and in good yields. After anchoring of the linker to a polymeric support, introduction of the first amino acid was achieved by reductive amination, giving a secondary amine. A following acylation of the secondary amine with a symmetrical amino acid anhydride resulted in a backbone amide linkage between the handle and the growing substrate (e.g., peptide chain). After solid-phase synthesis, the substrates could be released from the resin by either low acid conditions using 1% TFA in CH2Cl2 or high acid conditions such as 50% TFA in CH2Cl2. Peptide thioesters could be released from the T-BAL1 handle under very mild conditions using aqueous acetic acid. Tert-butyl based protecting groups, tert-butyl esters, tert-butyl ethers, and Boc groups, as well as dimethyl acetals were relatively stable to these mild conditions for release of the peptides.
