A Staudinger Approach towards Binol-Derived MAP-Type Bidentate P,N Ligands

Peptide cyclisation promoted by supramolecular complex formation

Phenol ester activated dipeptides that are reluctant to ring-close have been cyclised with the aid of sterically shielding metallo-porphyrins avoiding unwanted intermolecular reactions. The binding of ZnTPP to the dipyridine-functionalised activating phenolic ester was studied by NMR titrations and modelling. Staudinger-mediated cyclisations in the presence of ZnTPP increased the yield of the cyclic dipeptide from 16% to 40%.

Synthesis and coordination of a hybrid phosphinoferrocene sulfonamide ligand

A hybrid, phosphinoferrocene sulfonamide ligand was synthesised and studied as a ligand in Pd(ii) complexes, which were structurally characterised. Selected compounds were studied by cyclic voltammetry.

Efficient synthesis of (S,R)-Bn-Yanphos and Rh/(S,R)-Bn-Yanphos catalyzed asymmetric hydroformylation of vinyl heteroarenes

(S,R)-Bn-Yanphos/Rh-catalyzed asymmetric hydroformylation of vinyl heteroarenes and allyl-1H-indole has been achieved, affording the corresponding α-heteroaryl aldehydes with high enantioselectivities.

Competing amination and C–H arylation pathways in Pd/xantphos-catalyzed transformations of binaphthyl triflates: switchable routes to chiral amines and helicene derivatives

A Pd(OAc)₂/xantphos catalyst system can be tuned to promote either amination or C–H arylation of hindered binaphthyl 2-triflates, with xantphos's hemilability playing a key role.

Synthesis of new BINAP-based aminophosphines and their ³¹P-NMR spectroscopy

BINAP aminophosphines are prevalent N,P-bidentate, chiral ligands for asymmetric catalysis. While modification via the BINAP-nitrogen linkage is well explored and has provided a diverse body of derivatives, modification of the other substituents of the phosphorous center is another avenue in generating new congeners of this important class of chiral ligands. Herein reported are new BINAP aryl aminophosphines with electron rich or deficient substituents on the aryl rings. This scalable synthesis converted readily available starting material, (S)-BINOL, to a key intermediate (S)-NOBIN, from which the final chiral aminophosphines were prepared via a palladium-catalyzed, phosphonylation reaction. The aryl substituents are able to modify the electronic properties of the phosphorous center as indicated by the range of ³¹P-NMR shifts of these new ligands. A computational analysis was performed to linearly quantitate contributions to the ³¹P-NMR shifts from both resonance and field effects of the substituents. This correlation may be useful for designing and preparing other related aminophosphines with varying ligand properties.

Enantiomerically Pure 2-Bromo-2‘-diphenylphosphinyl-1,1‘- binaphthyl as a Monophosphorus Template for Electrophilic Functionalization in Chiral MOP-Type Ligand Synthesis

[reaction: see text] Pd-catalyzed monophosphinylation of (R)-2-bromo-2'-iodo-1,1'-binaphthyl with Ph(2)P(O)H afforded (R)-2-bromo-2'-diphenylphosphinyl-1,1'-binaphthyl in good yield with excellent chemoselectivity and no observable racemization. Subsequent lithiation in the presence of excess thiosulfonate furnished an enantiomerically pure sulfenylation product, which was reduced to afford a chiral S-MOP ligand.

Synthesis, structure and dynamics of methoxynaphthalene-substituted phospha-ruthenocenes and -ferrocenes

The syntheses of potassium 2-(2'-methoxynaphth-1'-yl)-3,4-dimethyl-5-phenylphospholide 4 and eta5-pentamethylcyclopentadienyl(eta5-2-(2-methoxynaphth-1-yl)-3,4-dimethyl-5-phenylphospholyl)-ruthenium(II)5 and -iron(II)6 are described. The barrier to rotation of the naphthyl group (79 kJ mol-1 and 72 kJ mol-1 in CD2Cl2 respectively) characterises 5 and 6 as potential tropos type ligands. Coordination of 5 to [PtCl2(PEt3)] gives two cis and two trans complexes [PtCl2(PEt3)5] wherein rotation about the phospholyl-naphthyl vector is slow.