Comparison of the reactivity of 2-amino-3-chloro- and 2,3-dichloroquinoxalines towards Ph2PH and Ph2PLi and of the properties of diphenylphosphanyl-quinoxaline P,N and P,P ligands

o-Hydroxyarylphosphanes: Strategies for Syntheses of Configurationally Stable, Electronically and Sterically Tunable Ambiphiles with Multiple Applications

o-Hydroxyarylphosphanes are fascinating compounds by their multiple-reactivity features, attributed to the ambident hard and soft Lewis- and also Brønstedt acid-base properties, wide tuning opportunities via backbone substituents with ±mesomeric and inductive, at P and in o-position to P and O also steric effects, and in addition, the configurational stability at three-valent phosphorus. Air sensitivity may be overcome by reversible protection with BH3 , but the easy oxidation to P(V)-compounds may also be used. Since the first reports on the title compounds ca. 50 years ago the multiple reactivity has led to versatile applications. This includes various P-E-O and P=C-O heterocycles, a multitude of O-substituted derivatives including acyl derivatives for traceless Staudinger couplings of biomolecules with labels or functional substituents, phosphane-phosphite ligands, which like the o-phosphanylphenols itself form a range of transition metal complexes and catalysts. Also main group metal complexes and (bi)arylphosphonium-organocatalysts are derived. Within this review the various strategies for the access of the starting materials are illuminated, including few hints to selected applications.

Serum-Stable Gold(III) Bisphosphine Complex Induces Mild Mitochondrial Uncoupling and In Vivo Antitumor Potency in Triple Negative Breast Cancer

The preparation of cyclometalated complexes offers a path to stable materials, catalysts, and therapeutic agents. Here, we explore the anticancer potential of novel biphenyl organogold(III) cationic complexes supported by diverse bisphosphine ligands, Au-1-Au-5, toward aggressive glioblastoma and triple negative breast cancer cells (TNBCs). The [C^C] gold(III) complex, Au-3, exhibits significant tumor growth inhibition in a metastatic TNBC mouse model. Remarkably, Au-3 displays promising blood serum stability over a relevant therapeutic window of 24 h and alteration in the presence of excess L-GSH. The mechanism-of-action studies show that Au-3 induces mitochondrial uncoupling, membrane depolarization, and G1 cell cycle arrest and prompts apoptosis. To the best of our knowledge, Au-3 is the first biphenyl gold-phosphine complex to uncouple mitochondria and inhibit TNBC growth in vivo.

Photoinduced Synthesis of Bisphosphinated Quinoxalines via Radical Cyclization of o-Diisocyanoarenes with Diphosphines

The cycloaddition reaction of o-diisocyanoarenes with interelement compounds under light is a very important reaction system to clarify whether this reaction proceeds by radical cyclization or by aza-Bergman cyclization. In this study, a series of diphosphines with phosphorus-phosphorus single bonds were selected as interelement compounds, and their cycloaddition reactions with o-diisocyanoarenes under light were investigated in detail to achieve a novel photoinduced synthesis of bisphosphinated quinoxalines via the radical cyclization pathway. In addition, the photoinduced reaction of diphosphines with isocyanides having o-functional groups such as cyano and ethenyl groups allowed us to elucidate the reaction pathway and product selectivity of this bisphosphination. Furthermore, the one-pot synthesis of Pd^II -quinoxaline complex was successfully achieved by applying the developed reaction.

3H-1,3-Azaphospholo[4,5-b]pyridines--novel heterocyclic P,N-bridging or hybrid ligands: synthesis and first d(8)-transition metal complexes

The first 3H-1,3-azaphospholo-pyridines 2a-c were synthesized as racemic mixtures in modest to medium yield by the reaction of N-(2-chloropyrid-3-yl)-trimethylacetimidoyl chloride 1 with RPLi2 (R = Ph, n-Bu, i-Bu), generated from RPH2 and BuLi in THF at -70 °C, and studied with respect to their suitability as ligands (L) in transition metal complexes. Reactions of 2a with group 6 metal(0) pentacarbonyls led to P-coordinated LM(CO)5 complexes 3a-5a (Cr, Mo, W) and the reaction of 2c with (norbornadiene)Mo(CO)4 surprisingly to 4c. [Rh(1,5-COD)Cl]2 and 2a,b, in metal/ligand ratio 1 : 1, furnished LRh(1,5-COD)Cl complexes 6a,b with P-coordination, 6b accompanied by a minor contamination by the bis-coordinated L[Rh(COD)Cl]2 complex 7b. Reactions of 2a,b with [(allyl)PdCl]2 proceeded in THF with dismutation of N-coordinated (allyl)PdCl and formed with 2a a labile crude product [(2a){(allyl)PdCl}1.2(PdCl2)0.8]·C4H8O, with the composition close to L[Pd(allyl)Cl]PdCl2 THF (8a·THF), which converted during crystallization to 9a, whereas 2b directly formed the N,N'-PdCl2-bridged bis[LPd(allyl)chloride] complex 9b. Conversion of 2b with equimolar amounts of Pd(CH3CN)2Cl2 in THF, or Na2PdCl4 in methanol, gave rise to the dimeric P,N-bridging complex 10b. Crystal structure analyses of 6a (rac), 9b·2CDCl3 (meso), 10b·4.5THF and 10b·2D6-acetone (rac) provided detailed structural information. 10b, but more efficiently complexes formed in situ from 2a,b and Pd2(DBA)3 or Pd(OAc)2, catalysed the arylamination of 2-bromopyridine with 2,4,6-trimethylaniline.