Synthesis, Reactivity, and Coordination of Semihomologous dppf Congeners Bearing Primary Phosphine and Primary Phosphine Oxide Groups

Abstract

This contribution reports the synthesis of two phosphinoferrocene ligands desymmetrized by an inserted methylene spacer, viz., a bis-phosphine combining primary and tertiary phosphine moieties in its structure, Ph2PfcCH2PH2 (2), and a structurally unique, stable phosphine-primary phosphine oxide Ph2PfcCH2P­(O)­H2 (7; fc = ferrocene-1,1′-diyl). Compounds 2 and 7, together with 1,1′-bis­(diphenylphosphino)­ferrocene (dppf), the bis-tertiary phosphine Ph2PfcCH2PPh2, and the adduct Ph2P­(BH3)­fcCH2PH2 (6), were studied as ligands in Ru­(II) complexes bearing auxiliary η6-arene ligands and both free ligands and the isolated complexes were structurally authenticated, using spectroscopic methods and X-ray crystallography, and further investigated by cyclic voltammetry. The results suggest that distinct donor moieties in the unsymmetric ligands differentiate the otherwise identical coordinated metal centers and that the phosphine moiety in phosphine-phosphine oxide ligand 7 is preferably coordinated to Ru­(II), before the phosphine oxide group, which must tautomerize into the hydroxyphosphine form prior to coordination.

Stable Pd(0) Complexes with Ferrocene Bisphosphanes Bearing Phosphatrioxaadamantyl Substituents Efficiently Catalyze Selective C‐H Arylation of Benzoxazoles by Aryl Chlorides

“…The semi‐homologous [11] bis‐phosphane 2 was synthesized by acid‐catalyzed condensation of air‐stable primary phosphane 6 [12] with acetylacetone (Scheme 3), similarly to the original preparation of CgPR (R=H, alkyl, Ph) reported by Epstein and Buckler [1] …”

“…All syntheses were performed in an inert atmosphere using standard Schlenk techniques and oven‐dried glassware. Compounds 4 , [34] 6 , [12] BrPCg, [3] and [Pd(ma)(N^N)] [35] were prepared according to the literature procedures. Syntheses of other starting materials and all phosphane selenides are described in Supporting Information.…”

Efficient Synthesis of Polysubstituted Furans through a Base‐Promoted Oxacyclization of (Z)‐2‐En‐4‐yn‐1‐ols

“…We are particularly interested in the synthesis of substituted furans from enynols because they are easily accessible substrates which can be variously functionalized. Cyclizations of enynols most often consist of the electrophilic activation of the alkyne catalyzed by a transition metal such as gold, [20c,e] palladium, [20b,c] copper [20a] or even ruthenium [24] . Another approach consists of the activation of the alcohol function by a base.…”

Primary Phosphines and Phosphine Oxides with a Stereogenic Carbon Center Adjacent to the Phosphorus Atom: Synthesis and Anti-Markovnikov Radical Addition to Alkenes

“…Organophosphorus compounds, and particularly those with three or four substituents on the phosphorus atom, i.e., tertiary phosphines, phosphine oxides, and their isologues, are of great importance in organic synthesis and medicinal chemistry [1][2][3]. The synthesis and reactions of primary phosphines [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and phosphine oxides [19][20][21] which contain two phosphorus-hydrogen (P-H) bonds have received increasing attention because these highly reactive bonds undergo various types of phosphorus-carbon (P-C) bond-forming reactions. Their highly efficient addition reactions to alkenes have been achieved with transition metal catalysts [22][23][24].…”