Ytterbium-BINOL complex

The first example for catalytic and enantioselective hydrophosphonylation of cyclic imines using cyclic phosphites is the lanthanide BINOL complex catalyzed hydrophosphonylation of 3-thiazolines. The pharmacologically interesting thiazolidinyl phosphonates are synthesized with excellent optical purities of up to 99% ee using the ytterbium-BINOL complex (116). 

NOL-based systems for addition of (substituted) anilines to meso epoxides. Hou found that a ytterbium-BI NO L complex catalyzed desymmetrization of cyclohexene oxide in up to 80% ee [15], Shibasaki demonstrated that a praseodymium-BINOL complex could promote addition of p-anisidine to several epoxides in moderate yields with modest enantioselectivities (Scheme 7.7) [16]. 

Molybdenum catalysts, Ruthenium porphyrins, Ruthenium(lll) complexes, Iron catalysts, Titanium catalysts. Sharpless epoxidation, Tungsten catalysts, Methyltrioxorhenium, Cobalt, Nickel, Platinum, Aerobic epoxidation, Lanthanum, Ytterbium, Calcium, BINOL-complexes. 2008 Elsevier B.v. 

Some of the metal-based catalysts used in the asymmetric hydrophosphonylation of aldehydes (see Section 6.4) can also be applied to the phosphonylation of imines. For instance, Shibasaki s heterobimetallic BINOL complexes work well for the catalytic asymmetric hydrophosphonylation of imines. In this case lanthanum-potassium-BINOL complexes (6.138) have been found to provide the highest enantioselectivities for the hydrophosphonylation of acyclic imines (6.139). The hydrophosphonylation of cyclic imines using heterobimetallic lanthanoid complexes has been reported. Ytterbium and samarium complexes in combination with cyclic phosphites have shown the best results in the cases investigated so far. For example, 3-thiazoline (6.140) is converted into the phosphonate (6.141) with 99% ee using ytterbium complex (6.142) and dimethyl phosphite (6.108). The aluminium(salalen) complex (6.110) developed by Katsuki and coworkers also functions as an effective catalyst for the hydrophosphonylation of both aromatic and aliphatic aldimines providing the resulting a-aminophosphonate with 81-91% ee. ... 

Markd and Evans have used ytterbium triflate complexes of BINOL and found that vinyl sulfide (8.119) provided the highest enantioselectivity in the inverse electron demand Diels-Alder reaction with the diene (8.120). ... 

Kobayashi reported an asymmetric Diels-Alder reaction catalyzed by a chiral lanthanide(III) complex 24, prepared from ytterbium or scandium triflate [ Yb(OTf)3 or Sc(OTf)3], (Zf)-BINOL and tertiary amine (ex. 1,2,6-trimethylpiperidine) [30], A highly enantioselective and endose-lective Diels-Alder reaction of 3-(2-butenoyl)-l,3-oxazolidin-2-one (23) with cyclopentadiene (Scheme 9.13) takes place in the presence of 24. When chiral Sc catalyst 24a was used, asymmetric amplification was observed with regard to the enantiopurity of (/ )-BINOL and that of the endoadduct [31 ]. On the other hand, in the case of chiral Yb catalyst 24b, NLE was affected by additives, that is, when 3-acetyl-l,3-oxazolidin-2-one was added, almost no deviation was observed from linearity, whereas a negative NLE was observed with the addition of 3-pheny-lacetylacetone. 

A chiral ytterbium complex formed from Yb(0-(-Pr)3 and 6,6 -diphenyl-BINOL catalyzed the asymmetric epoxidation of chalcone in 91% yield and 97% ee <2001TL6919>. A related reaction proceeds efficiently using enoates <2005JA8962>. 

Diels-Alder reactions. The version with inverse electron demand involving a-pyrones and vinyl ethers is subjected to asymmetric induction by a BINOL-ytterbium complex. 

Kobayashi has documented that chiral Yb complexes are also effective catalysts for nitrone cycloadditions (Scheme 18.19) [88]. In the presence of the putative ytterbium complex 98, derived from (S)-BINOL and chiral amine 99, the endo-isoxazolidine 100 was obtained in 96% ee. The chiral amine additive proved crucial for the observation of high enantioselectivity. Subsequently, the product 100 was readily converted into -lactam 101. 

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