Facile axial chirality control by using a precursor with central chirality. Application to the preparation of new axially chiral diphosphine complexes for asymmetric catalysis

Metallocene Sulfoxides as Precursors of Metallocenes with Planar Chirality

“…The best ligands are the diphosphine 62 and the sulfenyl phosphines 68, 84 and 86, giving ees of up to 98%. [18,48,54) Hydrosilylation of styrene (Scheme 19) catalyzed by a palladium/MOPF (69) complex gave up to 90 % ee. [55] The same complex allowed one to prepare 2,2'-dimethyl-1,1'-binaphthyl by an enantioselective Suzuki coupling with 54 % ee.…”

“…[47] Diphosphine 62 was prepared by Knochel from the ortho-lithium derivative 73 of sulfoxide 4a, and transmetallation with ZnBr 2 followed by a Negishi coupling with (2-iodophenyl)diphenylphosphine. [48] The subsequent sulfoxide-lithium exchange (with t-BuLi) and trapping by ClPPh 2 gave an overall yield of 60 % for 62. The two epimeric diphosphines 63 and 64 have been also synthesized by Knochel et al [49] The ortholithiated derivative of sulfoxide 4a was treated by 2-diphenylphosphanylbenzaldehyde, giving a mixture of epimeric alcohols, which were separated.…”

Metal-Catalyzed Cross-Coupling Reactions for Ferrocene Functionalization: Recent Applications in Synthesis, Material Science and Asymmetric Catalysis

“…Pedersen and Johannsen described the synthesis of compounds (27), leading after transformation to monophosphine ligands which showed high catalytic activities in hydrosilylation of styrene [27]. Starting from derivatives (28)-(30), Knochel's group reported the use of diphosphines and aminophosphines in palladium-catalyzed allylic alkylation and amination [28,29]. The sulfoxide group can be maintained in the molecule as described by Bäckvall's group in the synthesis of a new class of chiral ferrocene-based quinone ligands (31) and (32).…”

Phosphines and Related Tervalent Phosphorus Systems

“…Progress has also been made on the synthesis of ferrocenylphosphines bearing two or more phosphine groups. Among new systems reported are the diphosphinoferrocenophane (33), 65 the diphosphines (34) 66 and (35), 67 and the tetraphosphine 'manphos' (36). 68 New ferrocenyldiphosphines incorporating additional donor groups have been described, including the chiral C 2 -symmetrical system (37) 69 and a ferrocenyldiphosphine involving a chiral oxazoline group.…”

“…126 An efficient strategy for the synthesis of diphenylphosphino(trialkyl)stannanes in almost quantitative yield is afforded by the reaction of sodium diphenylphosphide (from the cleavage of triphenylphosphine in liquid ammonia) with chlorotrialkylstannanes. 127 Whereas displacement of chlorine from chlorosilanes by lithium mono(organo)phosphide reagents proceeds normally to give a series of silyl-substituted secondary phosphines, 128,129 the reaction of lithium bis(trimethylsilyl)phosphide with sterically crowded aryltrifluorosilanes results in the elimination of fluorotrimethylsilane and formation of the lithiophosphides (66). 130 The cyclic phosphine (67) has been obtained by treatment of a tris(2-iodoethyl)silane with dilithium phenylphosphide, and subsequently transformed in a series of steps to give the bicyclic system (68), having Me 3 P-like steric and electronic properties.…”