Diazaphospholene Precatalysts for Imine and Conjugate Reductions
作者:Matt R. Adams、Chieh-Hung Tien、Blake S. N. Huchenski、Michael J. Ferguson、Alexander W. H. Speed
DOI:10.1002/anie.201611570
日期:2017.5.22
The first examples of 1,3,2-diazaphospholene-catalyzed iminereduction and conjugate reduction reactions are reported. This approach employs readily synthesized alkoxydiazaphospholene precatalysts that can be handled in open air. Reduction of substrates containing Lewis basic functionality, isolated unsaturation, and protic functional groups was accomplished. The synthetic utility of this approach
Bulky 1,1′‐Ferrocenyl Ligands Featuring Diazaphospholene or Dioxaphosphepine Donor Fragments: Catalytic Screening in Nickel‐Catalyzed C‐N Cross‐Coupling
作者:Ryan. T. McGuire、Jillian S. K. Clark、Alexandre V. Gatien、M. Yue Shen、Michael J. Ferguson、Mark Stradiotto
DOI:10.1002/ejic.201900972
日期:2019.10.17
or diazaphospholene (L2) donor moieties have been prepared, crystallographically characterized, and tested in representative nickel‐catalyzed C–N cross‐coupling reactions. Ligand L1 proved competent in cross‐couplings involving primary/secondary alkylamine or indole nucleophiles with (hetero)aryl chlorides, with the catalytic performance of rac and meso‐L1 differing in the case of some substrate pairings
Application of Diazaphospholidine/Diazaphospholene-Based Bisphosphines in Room-Temperature Nickel-Catalyzed C(sp<sup>2</sup>)–N Cross-Couplings of Primary Alkylamines with (Hetero)aryl Chlorides and Bromides
作者:Alexandre V. Gatien、Christopher M. Lavoie、Raymond N. Bennett、Michael J. Ferguson、Robert McDonald、Erin R. Johnson、Alexander W. H. Speed、Mark Stradiotto
DOI:10.1021/acscatal.8b01005
日期:2018.6.1
donor fragment paired with an adjacent PR2 donor group (R = alkyl, aryl), whereby the incorporation of phosphorus into either a saturated or unsaturated heterocyclic ring serves as a means of modulating the donicity of the NHP fragment. Screening of these ancillary ligands in representative nickel-catalyzed C(sp2)–N cross-coupling test reactions allowed for the identification of one variant, featuring
P-Cyclopentadienyl-substituted 1,3,2-diazaphospholenes were prepared by salt metathesis from NaCp or LiCp* and 2-chloro-1,3,2-diazaphospholenes. Comprehensive spectroscopic and X-ray diffraction studies revealed a significant lengthening of the phosphorus–carbon bonds as compared with typical P–C bond distances, and the presence of fluxional molecular structures in solution and solid state as a consequence of circumambulatory migration of the diazaphospholene moiety around the Cp-ring. The P–C bond lengthening is accompanied by the capability to react with transition metal complexes under P–C bond activation and cyclopentadienyl transfer. At the same time, 2-Cp-diazaphospholenes react with strong bases under deprotonation to afford a phosphinyl–cyclopentadienide anion that reacts further with FeCl2 to a 1,1′-bisphosphinyl–ferrocene. The ambivalent behaviour of the diazaphospholenes offers interesting prospects to develop new synthetic methods for functional cyclopentadienyl complexes.
A Cation-Captured Palladium(0) Anion: Synthesis, Structure, and Bonding of [PdBr(PPh<sub>3</sub>)<sub>2</sub>]<sup>−</sup> Ligated by an N-Heterocyclic Phosphenium Cation
作者:Christine A. Caputo、Allison L. Brazeau、Zachery Hynes、Jacquelyn T. Price、Heikki M. Tuononen、Nathan D. Jones
DOI:10.1021/om9006278
日期:2009.9.14
Unsaturated N-heterocyclic phospheniumcations (uNHP) stabilize the [Pd0(PR3)2X]− anion proposed over the past decade to be the crucial but elusive intermediate in palladium-catalyzed cross-coupling reactions (X = halide). Insertion of metal into the P−Br bond of the precursor mesityl-substituted bromophosphine gives the structurally characterized Pd(0)-phosphenium complex (uNHPMes)Pd(PPh3)2Br, which