Synthesis of Enantiopure 1‐r‐Alkyl‐2‐c,5‐t‐Diphenylphospholanes and Phospholanium Salts through Direct Alkylation of Phospholane

Abstract

Chiral enantiopure 1-alkyl-2,5-diphenylphospholanium salts were obtained in one step through alkylation of phospholane with alkyl triflates. The resulting air-stable phosphonium salts are electron-rich trialkylphosphane precursor ligands for transition metals, and they offer a convenient route to-

Phosphines and related C–P bonded compounds

“…238 Returning to more fundamental aspects of nucleophilic attack by phosphorus at carbon, it is interesting to note a reinvestigation by Mathey's group of the reactions of 1-phenyl-3,4-dimethylphosphole with dimethyl acetylenedicarboxylate. In contrast to an earlier report, it has now been shown that the reaction of the phosphole with an excess of the ester in DCM at room temperature affords a surprisingly stable 1:2 phosphole-ester adduct, formulated as the ylide (129). When the reaction was carried out in the presence of silver nitrate, the intermediate 1:1 adduct was oxidised to the stable oxo-ylide (130), whose X-ray structure shows a highly zwitterionic character.…”

“…128 A simple route to chiral 1-alkylphospholanes (91, R ¼ alkyl) is provided by the alkylation of the parent phospholane (91, R ¼ H) using alkyl triflates, followed by treatment of the intermediate air-stable phospholanium salts with base. 129 The zwitterionic trialkylphosphonium sulphonates (92), air-stable precursors of t-alkylphosphine ligands, have been obtained by the reactions of dialkylphosphines with 1,3-propanesultone. 130 Secondary phosphines may also be used as nucleophiles in palladium-catalysed enantioselective allylic substitution reactions, leading to the allylic phosphines (93), 131 and also in base-catalysed reactions with 3-(1-arylsulfonylalkyl)indoles to give the related phosphinoalkylindoles.…”

Erfurt – Brücken der Gründerzeit

“…We noticed that the trialkyl‐substitution on phosphorus atom diminished the efficiency of the catalyst as the use of P‐alkylphosphane ligands 5 a – c required longer reaction time to reach full conversion as ligands 12. Furthermore, we observed modest asymmetric inductions, compared to P‐arylphospholane 3 a 13. This observation was subsequently confirmed by the use of the more electron‐rich ligand 3 j and its precursor 4 j prepared from oxide 1 j (Scheme ).…”

Regioselective Metal‐Catalyzed Hydrophosphinylation of Alkynes: Synthesis of Enantiopure α‐ or β‐Substituted Vinylphosphane Oxides

“…In our group, we are interested in the preparation of organophosphorus compounds based on the chiral trans ‐2,5‐diphenylphospholane10 moiety and their applications as ligands11 or chiral transfer agents 12. With this in mind, we commenced our study by a strategy to produce chiral enantiopure vinylphosphane by metal‐catalyzed hydrophosphinylation of alkynes (Scheme ).…”