Entropically Favorable Macrolactamization. Synthesis of Isodityrosine Peptide Analogues by Tandem Erlenmeyer Condensation−Macrolactamization

Total Synthesis of Bisbibenzyl Dibenzofuran Asterelin A via Intramolecular Oxidative Coupling

Total synthesis of asterelin A was accomplished by applying intramolecular Suzuki-Miyaura and oxidative couplings to the formation of an 18-membered macrocyclic ring and a dibenzofuran respectively.

Facile diversity-oriented synthesis of novel dipeptide mimetic compounds containing bioactive molecular skeletons under microwave irradiation

The diversity-oriented synthesis of dipeptide mimetic compounds embedded with bioactive molecular skeletons have been successfully established via microwave-assisted reactions between various 4-arylidene-2-phenyloxazol-5(4H)-ones and a broad scope of amines including aliphatic, aromatic, and heteroaromatic ones. This synthetic approach has prominent features of short reaction time, high yields, operational simplicity, as well as widespread applications, leading to a facile and straightforward access to structurally diverse dipeptide analogues with potential bioactivities. Moreover, the preliminary evaluation on the cytotoxic activity of this type of dipeptide derivatives has resulted in the finding of five compounds with stronger cytotoxicity than doxorubicin hydrochloride at the concentration of 10 μg/mL.

A general method for the synthesis of bastaranes and isobastaranes: first total synthesis of bastadins 5, 10, 12, 16, 20, and 21

A general strategy for the synthesis of twenty naturally occurring bastadins (all but bastadin 3) is presented. A key retrosynthetic disconnection of the two amide bonds, common in all target molecules, bisects the macrocyclic core into two diaryl ether fragments, an alpha,omega-diamine (western part) and an alpha,omega-dicarboxylic acid (eastern part). Efficient preparation of the synthetically challenging o-mono or dibromo-substituted diaryl ether linkages was achieved employing the diaryl iodonium salt method. Regarding the western part, variations of the aliphatic chain were more efficiently secured by the preparation of two different alpha,omega-aminonitrile moieties. Cobalt boride mediated reduction of the nitrile functionality established the required diamines and, at the same time, provided the necessary variation of the aromatic-ring bromination pattern. Regarding the eastern part, two different dicarboxyl precursors had to be prepared in order to accommodate bromination-pattern variations. Coupling and subsequent macrolactamization of different combinations of these key intermediates may lead at will to any member of this family of marine natural products. Four bastaranes (bastadins 5, 10, 12 and 16) and two isobastaranes (bastadins 20 and 21) were synthesized as a demonstration of the flexibility and efficiency of the approach presented.

Synthesis and chromatography of [CpRu]+-complexed bastadin precursors

The eastern and western diaryl ether portions of the macrocyclic bastadins, natural products from the marine sponge Ianthella sp., have been assembled as [CpRu]+ complexes. In an HPLC study, aminopropyl-functionalised silica was found as a very suitable stationary phase for the chromatographic separation of the different cationic ruthenium sandwich complexes. It is now possible for the first time to effectively monitor and purify [CpRu]+ complexes and to carry them through several synthetic steps.