Bis binaphtholate

Double couplings have been reported by Cummins [143] [bis(tributylstannyl)ethyne with aryl iodides], Tamao et al. [144] [tris(butylstannyl)phenylethyne with a dibromosilacyclo-pentadiene] and Diederich and co-workers [145] [tiis(butylstannyl)phenylethyne with an E-dibromoalkene]. Li et al. have obtained a bis(binaphthol) from a monoiodobinaphthol and bis(tributylstannyl)ethyne [146] in a yield of 66% (Scheme 4-42). 

BNP 1,1 Binaphtyl-2,2 -diyl phosphate, BNB BNB Bis(Binaphthol)-Boratej in the resolution or differentiation of chiral organometallic and coordination complexes through the formation of ion pairs with the appropriate enantiomer molecule, will be highlighted. 

Yamamoto and coworkers reported the synthesis of Brpnsted acids of chiral borate anions 4.34 and 4.35 made or derived from enantiopure BINOL (1,L binaphthalenyl2,2 -diol). The Bis(binaphthol)borate anion BNB (4.34) is configurationally stable and was used as chiral counter anion with some Cu(l) complexes to promote enantioselective asymmetric aziridination of styrene by Andtsen and coworkers (Scheme 4.4). ... 

Sn acetylides are frequently used for coupling. Coupling of Mn tricarbonyl complex of pentaiodocyclopentadiene (149) with trimethylpropynyltin afforded the pentapropynyl derivative 150 at room temperature [69], Symmetrically disub-stituted alkynes can be prepared by coupling of bis(tributylstaimyl)ethyne (152). The bis(binaphthol) derivative 153 was prepared by the reaction of 152 with the iodide 151 [70]. 

Based on acid-base combination chemistry, Shibasaki developed chiral heterobimetallic aluminium(m) lithium(i) bis(binaphtholate) (18), which can catalyse the enantioselective Michael reaction of cyclic enones with... 

Shibasaki developed the first catalytic enantioselective meso-epoxide ringopening reaction with 4-methoxyphenol (Scheme 2.15). ° This reaction was first found to be promoted by chiral gallium(m) lithium(i) bis(binaphtholate) (19), although the chemical yield was modest (31-75% yield) even with the... 

Moreover, chiral gallium(iii) sodium(i) bis(binaphtholate) 73 effectively catalysed Michael reactions in the presence of NaOt-Bu (Scheme 2.42). For example, the reaction of cyclohexenone with dibenzyl malonate catalysed by 73 provided the corresponding product in 45% yield with 98% ee, while the combined use of 73 and NaOt-Bu provided the Michael addition product in 87% yield with the same enantioselectivity. 

Some recent developments include the synthesis of poly-aryloxides based upon the binol nucleus. Examples include bis(binaphthol)methane and binaphthols containing phenolic substituents in the 3,3 -positions. ... 

Just as selective oxidation can be carried out on these systems, reduction also occurs with considerable selectively. Hydrogenation of binaphthol (Pd catalyst) in glacial acetic acid at room temperature for seven days affords the octahydro (bis-tetrahydro) derivative in 92% yield with no apparent loss of optical activity when the reaction is conducted on optically pure material. The binaphthol may then be converted into the bis-binaphthyl crown in the usual fashion. 

To overcome these problems with the first generation Brmsted acid-assisted chiral Lewis acid 7, Yamamoto and coworkers developed in 1996 a second-generation catalyst 8 containing the 3,5-bis-(trifluoromethyl)phenylboronic acid moiety [10b,d] (Scheme 1.15, 1.16, Table 1.4, 1.5). The catalyst was prepared from a chiral triol containing a chiral binaphthol moiety and 3,5-bis-(trifluoromethyl)phenylboronic acid, with removal of water. This is a practical Diels-Alder catalyst, effective in catalyzing the reaction not only of a-substituted a,/ -unsaturated aldehydes, but also of a-unsubstituted a,/ -unsaturated aldehydes. In each reaction, the adducts were formed in high yields and with excellent enantioselectivity. It also promotes the reaction with less reactive dienophiles such as crotonaldehyde. Less reactive dienes such as isoprene and cyclohexadiene can, moreover, also be successfully employed in reactions with bromoacrolein, methacrolein, and acrolein dienophiles. The chiral ligand was readily recovered (>90%). 

Kobayashi et al. have reported the use of a chiral lanthanide(III) catalyst for the Diels-Alder reaction [51] (Scheme 1.63, Table 1.26). Catalyst 33 was prepared from bi-naphthol, lanthanide triflate, and ds-l,2,6-trimethylpiperidine (Scheme 1.62). When the chiral catalyst prepared from ytterbium triflate (Yb(OTf)3) and the lithium or sodium salt of binaphthol was used, less than 10% ee was obtained, so the amine exerts a great effect on the enantioselectivity. After extensive screening of amines, ds-1,2,6-... 

Chiral C2-symmetric ansa-metallocenes, also referred to as bridged metallocenes, find extensive use as catalysts that effect asymmetric C—C bond-forming transformations [4]. In general, bridged ethylene(bis(tetrahydroindenyl))zirconocene dichloride ((ebthi)ZrCl2) 1 or its derived binaphtholate ((ebthi)Zrbinol) 2 [5] and related derivatives thereof have been extensively utilized in the development of a variety of catalytic asymmetric alkene alkylations. 

A fluorous version of the chiral bis-phosphine BINAP has been developed for asymmetric Heck reactions [5], Several fluorous-derivatized binaphthols and BINAP derivatives have been reported, (Scheme 10.4) [6], The silane spacer group present in one of the ligands was used to maximize the percentage fluorine on the molecule. Even so, the partition coefficient1 between FC-72 (see Chapter 3) and benzene was only 2.85, and not surprisingly, the reuse of the catalyst was poor. 

With Chiral Al Complexes Chiral bis(silyl)binaphthol-modified aluminum catalyst, which is originally developed for asymmetric hetero-Diels-Alder reaction [50], is successfully applied to asymmetric Diels-Alder reaction of cyclopentadiene with methyl acrylate or methyl propio-late [51 ] (Eq. 8A.28). The latter is a rather rare example in the literatures. 

A chiral bis(silyl)binaphthol-modified aluminum catalyst has been successfully applied to the asymmetric [2+2] cycloaddition of ketenes to aldehydes, giving optically active 4-substi-tuted oxetan-2-ones with moderate enantioselectivity [69] (Eq. 8A.45). 

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