Chirality control in 2,2′-biphosphole ligand leading to enantiopure Pd complexElectronic supplementary information (ESI) available: selected spectroscopic NMR data. See http://www.rsc.org/suppdata/cc/b3/b301613g/

Abstract

Asymmetric alkylation of the 3,4-dimethyl-5-phenyl-2,2'-biphospholyl anion with the (2R,4R)-(-)-pentaneditosylate leads to a new chirally flexible 2,2'-biphosphole ligand as a mixture of three diasteroisomers. By complexation with Pd(II), a chirality control occurs to afford enantiopure Pd complex.

The Continuing Development of the Chemistry of Phospholes

“…Unlike the oxides, phosphine sulfides are quite stable and do not dimerize at moderate temperatures. Some newly prepared phosphine sulfides include 212 ( 56.4) [14], 213 ( 54.6) [14], 214 ( 55.0) [14], 215 ( 51.25) [33], 216 ( 49.2) [43], 217 (as a mixture of isomers, 50.75 and 51.37 [31]), and 218 (three diastereomers) [38].…”

“…The P-P bond in 1,1'-biphospholes can be cleaved by reaction with sodium in THF at room temperature, as seen in the new examples of Equation 24 [37], or by sodiumnaphthalene (Equation 25) [38]. In both cases the anions were alkylated to form new derivatives 75 ( -0.2) and 78 (as three diastereomers with 18,16 and a doublet of doublets, 31 and 27 with J=42 Hz).…”

Chiral diphosphines and diphosphinites derived from 2,2-biphosphole: Stereodynamic ligands for asymmetric catalysis

“…8 These unidentified products are palladium complexes with four diastereotopic phosphorus having opposite phosphorus configurations according to 31 P NMR. 9 This lack of changes shows that the energy barrier for the stereochemical interconversion is higher than $18 kcal/mol at 85 8C.…”

“…Some years ago, we reported the first application of the chiral stereochemically dynamic 2,2'-biphophole ligand (BIPHOS) to asymmetric allylic substitution involving crystallization-induced spontaneous resolution and kinetic stabilization by coordination to Pd centre 2 [9]. In a more convenient procedure, we have discovered that a dual chirality control can be achieved by introducing a chiral linker between the two phosphorus atoms that favours a single enantiomeric form upon coordination to a metal [10].…”

Phosphines and Related Tervalent Phosphorus Systems

“…By complexation with Pd(II), a chirality control occurs to give an enantiopure complex. 798 The electronic properties of homo-and hetero-oligomers and -polymers involving phosphole rings has continued to attract interest, and a review of their chemistry has appeared. 799 New alternating a,a-thiophene-phosphole oligomers up to seven rings in length have been prepared, the HOMO-LUMO gap decreasing as the length of the conjugated system increases.…”