Charge and Potential: Arenes as Oxidants

Abstract

ether phase decanted. The precipitate was washed several times with ether and finally dried to give the deprotected product as a white powder (13 mg. 91 %). The reductive amination was carried out using a modification of a published procedure [13]. In a typical experiment, the protected peptide la (10 pmol) was dissolved in 2 mL of a 10: 1 mixture of 0.1 M phosphate buffer (pH 6.0) and CH3CN. To this peptide solution were added the carbohydrate (200 pmol) dissolved in 2 mL of the Same buffer and sodium cyanoborohydride (200 pmol) as a solid. The mixture was stirred at room temperature and progress of the coupling reaction monltored by analytical HPLC. The glycopeptides were purified by semipreparative HPLC and characterized by ESI-MS. syntheses solid-phase[l] I.

New Synthetic Routes to C‐Amino Phosphorus Ylides and their Subsequent Fragmentation into Carbenes and Phosphines

“…[13] Interestingly, basic phosphines, such as tricyclohexylphosphine, are not required, triphenylphosphine can be used. One can quickly realize that these onio-substituted aldiminium salts 1 are oxidized forms of the corresponding ylides 2.…”

“…Dry, oxygen-free solvents were employed. 1 H, 13 C and 31 P NMR spectra were recorded on Varian Inova 300, 500 and Bruker Avance 300 spectrometers.…”

2,3,5,6‐Tetrafluoro‐p‐phenylenebis(phosphanes) – Preparation and Structure of an Electron‐Poor P–RF–P Linker

“…[21][22][23] The latter are, however, not available for further functionalization at the phosphorus atoms, except for the transformation to the corresponding phosphoranes. [24,25] A general route towards the synthesis of dichlorophosphanes includes the reaction of the corresponding R-M (M = Li or MgBr; R = organic substituent) compound with an excess of PCl 3 , if steric protection of R is sufficient to prevent multiple substitution at the phosphorus atom. Recently, we investigated the reaction of 2,3,5,6-F 4 C 6 HLi with PCl 3 and observed the formation of a mixture of multiplesubstituted phosphanes [PCl n (C 6 F 4 H) 3-n ] even if a 10-fold excess of PCl 3 was used.…”

Nucleophilic Aromatic Substitution with 2,3-Dihydro-1,3-diisopropyl- 4,5-dimethylimidazol-2-ylidene

“…More recently, this type of reaction has been extended to perfluorinated arenes predominantly by reactions with anionic nucleophiles [3,4]. Much less is known on the substitution of fluoride by neutral nucleophiles such as amines [5] and in situ prepared nucleophilic carbenes [6].…”