Peptides are steadily gaining importance as pharmaceutical targets, and efficient, green methods for their preparation are critically needed. A key deficiency in the synthetic toolbox is the lack of an industrially viable peptide desulfurization method. Without this tool, the powerful native chemical ligation reaction typically used to assemble polypeptides and proteins remains out of reach for industrial preparation of drug targets. Current desulfurization methods require very large excesses of phosphine reagents and thiol additives or low-abundance metal catalysts. Here, we report a phosphine-only photodesulfurization (POP) using near-UV light that is clean, high-yielding, and requires as little as 1.2 equiv phosphine. The user-friendly reaction gives complete control to the chemist, allowing solvent and reagent selection based on starting material and phosphine solubility. It can be conducted in a range of solvents, including water or buffers, on protected or unprotected peptides, in low or high dilution and on gram scale. Oxidationprone amino acids, π-bonds, aromatic rings, thio-aminal linkages, thioesters, and glycans are all stable to the POP reaction. We highlight the utility of this approach for desulfurization of industrially relevant targets including cyclic peptides and glucagon-like peptide 1 (GLP-1(7-36)). The method is also compatible with NCL buffer, and we highlight the robustness of the approach through the one-pot disulfide reduction/multidesulfurization of linaclotide, aprotinin, and wheat protein.

A concise strategy is described for the synthesis of ailanthoidol (1), egonol (2), homoegonol (3), demethoxyegonol (4), demethoxyhomoegonol (5), and stemofuran A (6). This approach involves a Pd‐catalysed domino cyclization/coupling process using triarylbismuth reagents for the generation of the benzofuran core. Subsequent structural modifications then give the final targets. The high yielding synthesis of the recently isolated natural products egonol‐9(Z)‐12(Z)‐linoleate (2a), 7‐demethoxyegonol‐9(Z)‐12(Z)‐linoleate (4a), and 7‐demethoxy‐egonol‐9(Z)‐oleate (4b) are also reported.

The protecting group manoeuvring as a strategy was applied for tuning the stability and reactivity of 4-(2,2-dibromovinyl)benzene-1,3-diol (12a) and 6-(2,2-dibromovinyl)-2,2-dimethylchroman-7-ol (22) in the domino synthesis of benzofuran-based natural products (1-8). The functional group demands and their impact on the reactivity driven by electronic effects were successfully managed by varying the protecting groups with substituted gem-dibromovinylphenols in domino couplings and triarylbismuth reagents under palladium-catalyzed conditions. This approach paved the way for the synthesis of moracin M (1) and cicerfuran (2), and the first time synthesis of moracin D (3) and moracin E (4) along with chromene-fused benzofuran-based natural products (5-8) in overall good yields.

Pd-catalyzed coupling of 1,3-dienyldibromides with triarylbismuths was demonstrated for the synthesis of a diverse range of 1,3-enynes. This study provided easy access to a range of functionalized 1,3-enynes in high yields utilizing triarylbismuths in sub-stoichiometric amounts. A new and concise route was unveiled for the synthesis of extended p-conjugated molecular systems with the help of chemoselective couplings and in conjunction with Sonogashira, Heck and arylation reactions under combined catalysis.