Amino acids surrogates: an indirect method for the synthesis of peptides containing the thioasparaginyl residue

The protected pentapeptide, Boc-Tan-Cys(PMB)-Pro-Leu-GlynH₂¹ and related thioasparaginyl compounds were prepared by an indirect method from their corresponding β-cyanoalanyl precursors by treatment with H₂S/NH₃. The optical purities of thioasparagine (Tan) derivatives were evaluated by two different approaches.     

Application of polymer-bound 4-(bromomethyl)-3-nitrobenzoic acid for synthesis of trisubstituted 1,4-benzodiazepine-2,3-diones

A method utilizing polymer-bound 4-(bromomethyl)-3-nitrobenzoic acid as a key precursor leading to 1,4-benzodiazepin-2,3-dionescaffold is described. It involves afour-step sequence including nucleophilic displacement,acylation, simultaneous reduction-cyclization and alkylation,providing rapid access to the title compounds in excellent yieldand purity.     

Solid-phase synthesis of tetrahydro-1,4-benzodiazepin-2-one derivatives

An efficient method for solid-phase construction of tetrahydro-1,4-benzodiazepin-2-one scaffold is described. Polymer-bound 4-(bromomethyl)-3-nitrobenzoic acid was reacted with alpha-amino acid methyl esters, followed by nitro group reduction and hydrolysis. Subsequent intramolecular cyclization and alkylation at N(4) afforded the structurally diverse products in high yields and excellent purities.