1,1′‐Binaphthyl‐2,2′‐diamine‐Based Chiral Phosphorous Triamides: Synthesis and Application in Asymmetric Catalysis

Abstract

A set of chiral monodentate phosphorous triamides (PTA) comprising 1,1′‐binaphthyl‐2,2′‐diamine as the common moiety have been synthesised. Electronic and steric tuning of the ligands was achieved by variation of the substituents at the diamine nitrogen atoms by incorporating methyl, p‐tolyl and tosyl groups. Both chiral and achiral building blocks were used as monoamine components. Notably, (11bR)‐3,5‐dimethyl‐N,N‐bis[(S)‐1‐phenylethyl]‐3,5‐dihydro‐4H‐dinaphtho[2,1‐d:1′,2′‐f][1,3,2]diazaphosphepin‐4‐amine, which is the PTA most closely related to the Feringa phosphoramidite ligand, was synthesised and characterised by NMR spectroscopy and X‐ray diffraction. This PTA displays increased conformational rigidity in comparison with the corresponding phosphoramidite and adopts a C1‐symmetric structure both in the solid state and in solution, even at room temperature. The new PTA ligands were used in the copper‐catalysed conjugate addition of diethylzinc to cyclohex‐2‐enone and the nickel‐catalysed hydrovinylation of styrene giving good activities and chemoselectivities at moderate enantioselectivities in both reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

New Enantiopure P,P-Bidentate Bis(diamidophosphite) Ligands. Application in Asymmetric Rhodium-Catalyzed Hydrogenation

“…20 A set of closely related chiral phosphorus triamides based on the 1,1′-binaphthyl-2,2′diamine backbone and their application in the copper-catalyzed conjugate addition of diethylzinc to cyclohex-2-enone and the nickel-catalyzed hydrovinylation of styrene that yield good activities and chemoselectivities and moderate enantioselectivities in both reactions have also previously been described. 26 On the basis of the observation that chiral bidentate diamidophosphites are effective ligands for the Rh-asymmetric hydrogenation, 23 we describe here the synthesis of a series of modular chiral bis(diamidophosphite) compounds with the general formula shown in Figure 2, which have been designed to ensure systematic modifications of the ligands. Their corresponding cationic rhodium(I) complexes were prepared and fully characterized.…”

NOBIN-based phosphoramidite and phosphorodiamiditeligands and their use in asymmetric nickel-catalysed hydrovinylation

“…The synthesis of the phosphorodiamidites of type A was carried out using a protocol established for the phosphoramidites 14 or phosphorous triamide 7,8 congeners (Scheme 1). Adding an equimolar amount of (S a )-N-Ph-NOBIN to enantiopure 1,1-dichloro-N,N-bis(1-phenylethyl)phosphinamine (S C ,S C )-1 at 0 1C in CH 2 Cl 2 in the presence of NEt 3 resulted in the formation of two P-containing products, which could be separated through column chromatography and isolated in pure form (vide infra).…”

“…2 In particular, BINOL-based (BINOL = 1,1 0 -binaphthyl-2,2 0 -diol) phosphoramidites are excellent chiral auxiliaries for a variety of asymmetric metalcatalysed reactions when used as monodentate ligands 3 as well as in combination with a second donor group within the same molecule 4 or with a second ligand. 5 More recently, several groups synthesised phosphorous triamides based on variously substituted 2,2 0 -diamino-1,1 0 -binaphthyl backbones [6][7][8] and applied them in catalysis, albeit without reaching the efficiency level of the related phosphoramidites. A small number of monodentate phosphorodiamidite (diamido phosphite) ligands have also been synthesised, either from diamines and an alcohol or amino alcohols and amines.…”

The Synthesis of Chiral Phosphorus Ligands for use in Homogeneous Metal Catalysis

“…[21] For the investigation of this structural relation, Franciò and Leitner prepared phosphorous triamides by reaction of equimolar amounts of secondary amines with PCl 3 (Scheme 1). [22] The resulting dichlorophosphorous amidites were reacted with atropisomeric C 2 -symmetric diamines in the second step. Remarkably the reverse order did not succeed.…”

“…[18] Also in the last few years, further progress can be noted, partly caused by new insights in the reaction mechanism mainly derived from theoretical studies. [22] The resulting dichlorophosphorous amidites were reacted with atropisomeric C 2 -symmetric diamines in the second step. [20] One of the most frequently used modifications is the incorporation of substituents in 3,3'-positions of the binaphthyl unit (Figure 1).…”