A palladium-catalyzed, intermolecular Heck-type coupling of alkyl iodides and alkenes is described. This process is successful with a variety of primary and secondary unactivated alkyl iodides as reaction partners, including those with hydrogen atoms in the β position. The mild catalytic conditions enable intermolecular C-C bond formations with a diverse set of alkyl iodides and alkenes, including substrates containing base- or nucleophile-sensitive functionality.
A manganese-catalyzed carboacylation of alkenes with alkyl iodides and carbon monoxide is described. This carbonylative difunctionalization uses both primary and secondary alkyl iodides in reactions with a diverse array of cyclic and acyclic substrates. Examples of successful applications to the synthesis of 5-, 6-, and 7-membered rings are provided. The inexpensive, first-row catalytic system and mild reaction conditions are expected to facilitate applications in complex synthesis.
Recognition of distinct glycans is central to biology, and lectins mediate this function. Lectin glycan preferences are usually centered on specific monosaccharides. In contrast, human intelectin-1 (hItln-1, also known as Omentin-1) is a soluble lectin that binds a range of microbial sugars, including β-Dgalactofuranose (β-Galf), D-glycerol 1-phosphate, D-glycero-D-talo-oct-2-ulosonic acid (KO), and 3deoxy-D-manno-oct-2-ulosonic acid (KDO). Though these saccharides differ dramatically in structure, they share a common feature-an exocyclic vicinal diol. How and whether such a small fragment is sufficient for recognition was unclear. We tested several glycans with this epitope and found that L-glycero-α-Dmannoheptose and D-glycero-α-D-manno-heptose possess the critical diol motif yet bind weakly. To better understand hItln-1 recognition, we determined the structure of the hItln-1•KO complex using X-ray crystallography, and our 1.59-Å resolution structure enabled unambiguous assignment of the bound KO conformation. This carbohydrate conformation was present in >97% of the KDO/KO structures in the Protein Data Bank. Bioinformatic analysis revealed that KO and KDO adopt a common conformation, while heptoses prefer different conformers. The preferred conformers of KO and KDO favor hItln-1 engagement, but those of the heptoses do not. Natural bond orbital (NBO) calculations suggest these observed conformations, including the side chain orientations, are stabilized by not only steric but also stereoelectronic effects. Thus, our data highlight a role for stereoelectronic effects in dictating the specificity of glycan recognition by proteins. Finally, our finding that hItln-1 avoids binding prevalent glycans with a terminal 1,2 diol (e.g., NeuAc, and L-glycero-α-D-manno-heptose) suggests the lectin has evolved to recognize distinct bacterial species. File list (3) download file view on ChemRxiv McMahonIsabella1_4_20_LLK.pdf (2.17 MiB) download file view on ChemRxiv SuppInfo01_4_19_Final.pdf (3.02 MiB) download file view on ChemRxiv McMahonIsabella1_4_20_LLK.docx (2.61 MiB)
A palladium‐catalyzed, intermolecular Heck‐type coupling of alkyl iodides and alkenes is described. This process is successful with a variety of primary and secondary unactivated alkyl iodides as reaction partners, including those with hydrogen atoms in the β position. The mild catalytic conditions enable intermolecular CC bond formations with a diverse set of alkyl iodides and alkenes, including substrates containing base‐ or nucleophile‐sensitive functionality.
Recognition of distinct glycans is central to biology, and lectins mediate this function. Lectin glycan preferences are usually centered on specific monosaccharides. In contrast, human intelectin-1 (hItln-1, also known as Omentin-1) is a soluble lectin that binds a range of microbial sugars, including β-Dgalactofuranose (β-Galf), D-glycerol 1-phosphate, D-glycero-D-talo-oct-2-ulosonic acid (KO), and 3- deoxy-D-manno-oct-2-ulosonic acid (KDO). Though these saccharides differ dramatically in structure, they share a common feature—an exocyclic vicinal diol. How and whether such a small fragment is sufficient for recognition was unclear. We tested several glycans with this epitope and found that L-glycero-α-Dmanno- heptose and D-glycero-α-D-manno-heptose possess the critical diol motif yet bind weakly. To better understand hItln-1 recognition, we determined the structure of the hItln-1·KO complex using X-ray crystallography, and our 1.59-Å resolution structure enabled unambiguous assignment of the bound KO conformation. This carbohydrate conformation was present in >97% of the KDO/KO structures in the Protein Data Bank. Bioinformatic analysis revealed that KO and KDO adopt a common conformation, while heptoses prefer different conformers. The preferred conformers of KO and KDO favor hItln-1 engagement, but those of the heptoses do not. Natural bond orbital (NBO) calculations suggest these observed conformations, including the side chain orientations, are stabilized by not only steric but also stereoelectronic effects. Thus, our data highlight a role for stereoelectronic effects in dictating the specificity of glycan recognition by proteins. Finally, our finding that hItln-1 avoids binding prevalent glycans with a terminal 1,2 diol (e.g., NeuAc, and L-glycero-α-D-manno-heptose) suggests the lectin has evolved to recognize distinct bacterial species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.