ABSTRACT
The straightforward entry to benzofuroindoline containing natural product-like scaffolds has been achieved by a challenging [3 + 2] oxidative coupling between phenols and indoles. The reaction proceeds by NIS-oxidation of the indole followed by the trapping of the resulting electrophilic intermediate by phenol.
Subject(s)
Benzofurans/chemistry , Indoles/chemistry , Phenols/chemistry , Catalysis , Molecular Structure , Oxidation-ReductionABSTRACT
A general strategy for the amino acid homologation via Blaise reaction and subsequent reduction is presented. This strategy involves the preparation of protected alpha-amino nitriles from the corresponding amino acids, followed by the zinc-mediated condensation of tert-butyl bromoacetate, to give the imidazolidones after iminozincate cyclization. Reduction gave the saturated imidazolidinones with cis or trans stereochemistry, depending on the reduction conditions. This strategy was applied to nonfunctionalized amino acids and to functionalized amino acids such as serine and aspartic acid. Additionally, acidic hydrolysis of cis or trans imidazolidinones to the corresponding chiral 4-aminopyrrolidones is described.
Subject(s)
Amino Acids/chemistry , Heterocyclic Compounds/chemical synthesis , Imidazolidines/chemical synthesis , Nitriles/chemistry , Pyrrolidinones/chemical synthesisABSTRACT
Pyrinodemin A 1, a cytotoxic marine alkaloid, was synthesized in a convergent and enantioselective fashion. The key steps are an asymmetric intramolecular dipolar cycloaddition of an oxazoline N-oxide to introduce the bicyclic ring system of the molecule, a cuprate coupling for the extension of the saturated chain and a B-alkyl Suzuki coupling for the introduction of a 3-pyridyl moiety. Reductive amination allowed the coupling of the second side-chain onto the nitrogen atom to give 1. Additionally, attempts to prepare 1 from a trienic precursor by a double B-alkyl Suzuki reaction are described.
Subject(s)
Oxazoles/chemical synthesis , Pyridines/chemical synthesis , Molecular Conformation , Oxazoles/chemistry , Pyridines/chemistry , StereoisomerismABSTRACT
Novel derivatives of the marine alkaloid bengacarboline have been synthesized. The seco derivatives 11 and 12 were evaluated for topoisomerase inhibition, DNA damages, cytotoxicity and cell cycle perturbation. The two synthetic analogs are more potent cytotoxic agents than bengacarboline and they both induce an accumulation of cells in the S phase of DNA synthesis. They do not function as topoisomerase inhibitors but trigger DNA damages in cells.
