Synthesis and biological evaluation of the ascidian blood-pigment halocyamine A

Abstract

Synthesis of the antimicrobial marine natural product halocyamine A has been achieved utilizing a combination of Sonogashira coupling, ruthenium complex/ytterbium triflate catalyzed hydroamidation and solid-phase peptide synthesis (SPPS) chemistry. The synthetic natural product exhibited only modest levels of antibacterial activities but significant antioxidant activity.

Synthesis of Amides from Aliphatic Acids and Amines by using of I2/TBHP at Room Temperature

“…After the optimization study, the generality of the optimized conditions with differently substituted amines was investigated (Scheme ) . Substituted aromatic amines react with acetic acid gave moderate to good yields along with corresponding amines, like 4‐methyl, 3‐ methyl, 4‐methoxy, and 3‐methoxy gave 68, 71, 65, and 68% of yields in corresponding products ( 4 b–4 d ).…”

Marine natural products

“…Further work is required to clarify these ndings. The structures of a number of NPs have been conrmed by total synthesis including halocyamine A, 664 biselides A 665 and E, 666 ningalin G, 667 (+)-arborescidine C, 668 and (À)-pseudodistomin E. 669 Absolute conguration was assigned to the phosphorylated polyketide phospoeleganin (Sidnyum elegans) by synthesis of model fragment alicyclic compounds and their cyclic derivatives, and comparison of 1 H and 13 C NMR chemical shis. 670 Improved semisyntheses of ecteinascidin 743 and (À)-jorumycin from safracin B have been reported.…”

Harnessing Stereospecific Z-Enamides through Silver-Free Cp*Rh(III) Catalysis by Using Isoxazoles as Masked Electrophiles

“…The secondary enamides have received immense attention in synthetic organic chemistry due to their pervasiveness in various bioactive natural products and a range of marine metabolites . Moreover, assessing the stability and polarizability of the enamides, they have been used as versatile synthetic intermediates for the synthesis of heterocycles, in cross-couplings/Heck reactions, in asymmetric hydrogenation/halogenation, and recently in C–H functionalization .…”