Regioselective intramolecular N1–C3 cyclizations on pyrrole–proline to ABC tricycles of dibromophakellin and ugibohlin
摘要:
Pyrrole N1-C and C3-C regioselective linkage to the fused tricycle ABC system present in the marine metabolites ugibohlin and dibromoisophakellin is described. The cyclization is closely dependent oil the electrophilic function. bromination degree of the pyrrole moiety and pH conditions. The mechanism of the functionalization of the ABC olefin by oxidative agents was found to occur through an N-acyliminium intermediate as showed by the natural chemical connection between ugibohlin and dibromoisophakellin. (C) 2004 Published by Elsevier Ltd.
A new procedure for the aerobic oxidation of α‐amino acids acylated by pyrrole‐carboxylic acid with triplet dioxygen is introduced. The reaction is general for a variety of pyrrole‐amino acid derivatives and represents a very practical and controllable method for the selective preparation of α‐hydroperoxy‐ or α‐hydroxy‐α‐amino acid diketopiperazines with molecular dioxygen. Furthermore, the non‐catalyzed
A Likely Biogenetic Gateway Linking 2-Aminoimidazolinone Metabolites of Sponges to Proline: Spontaneous Oxidative Conversion of the Pyrrole-Proline-Guanidine Pseudo-peptide to Dispacamide A
作者:Nathalie Travert、Ali Al-Mourabit
DOI:10.1021/ja047574e
日期:2004.8.1
new spontaneousoxidative transformation of the associated pyrrole-proline-guanidine to the natural marine pyrrole 2-aminoimidazolinone derivative has been achieved. The sensitive reaction requires air oxygen and the N-acylation of proline by pyrrole-2-carboxylic acid. Proline metabolism and pyrrole 2-aminoimidazole secondary metabolites formation seem to be related and are utilized by sponges under
Divergent Synthesis of Bisphenols and Diaryl Ethers by Metal Compatible Organocatalytic Aerobic Oxidation of Boronic Acids
作者:Kyriaki Gennaiou、Marina Petsi、Basil Kakarikas、Nikos Iordanidis、Alexandros L. Zografos
DOI:10.1002/adsc.202200575
日期:2022.9.6
Hantzsch ester and HFIP is compatible with copper(II) salts for the activation of dioxygen. These findings allow to selectively diverge the oxidation profile of boronic acids for the synthesis of phenols, bisphenols and diarylethers by DKP-promoted aerobic oxidation and subsequent metal oxidative-coupling or Chan-Lam-Evans type reaction of the formed phenols.
New debromopyrrole-2-aminoimidazolones, debromodispacamide B (1) and debromodispacamide D (2) were isolated from the sponge Agelas mauritiana, collected in the Solomon Islands. A biomimetic one-step reaction from pseudopeptides 5 and 13 in presence of air oxygen and guanidine gave the chiral form of the natural product stereoselectively.
Organocatalytic epoxidation and allylic oxidation of alkenes by molecular oxygen
作者:Marina Petsi、Maria Orfanidou、Alexandros L. Zografos
DOI:10.1039/d1gc03029a
日期:——
reduction of dioxygen by Hantzsch ester under mild conditions to allow the aerobic metal-free epoxidation of electron-rich alkenes. Mechanistic crossovers are underlined, explaining the dual role of Hantzsch ester as a reductant/promoter of the DKP catalyst and a simultaneous competitor for the epoxidation of alkenes when HFIP is used as a solvent. Expansion of this protocol to the synthesis of allylic alcohols