BINOL-derived

Table 1.13 BINOL-derived phase-transfer catalysts for asymmetric Darzens reactions.

The following order of initiation rate constants was found by Grubbs et al. for 71a and some precatalysts containing one phosphine ligand 56d< 56k 71a<56h (cf. Scheme 15 for structures of 56d,h,k) [48b, 55]. Thus, 71a shows a rate of initiation comparable to that of 56k but three orders of magnitude higher than that of 56d. Nevertheless, 56d appears to be more reactive in RCM reactions than 71a [56]. Wakamatsu and Blechert were the first to report that the activity of precatalysts related to 71a can be dramatically enhanced by modification of the benzylidene unit [56]. For example, RCM of 75 using 1 mol% of BINOL-derived complex 71b yields the azacyclic product 76 in quantitative yield within 20 min (Eq. 10), whereas with 56d only 4% of 76 was obtained under these conditions [56]. 

Scheme 1.53 Test reaction with BINOL-derived A -phosphino sulfoximines.

On the other hand, Bolm et al. have reported, more recently, the use of BINOL-derived A -phosphino sulfoximines as ligands in the rhodium-catalysed hydrogenation of dimethyl itaconate and a-acetamidoacrylates, achieving excellent enantioselectivities of up to 99% ee (Scheme 8.12). In the main... 

Scheme 9.21 Rh- and Ru-catalysed reductions of acetophenone with BINOL-derived S/P ligands.

On the other hand, S/0 ligands have been developed to a much lesser extent, although the high efficiency of BINOL-derived hydroxysulfoxides was demonstrated by Shibasaki s group in 2004 for the Reissert reaction. 

Halogenated BINOL derivatives of Zr(0-f-Bu)4 such as 19 also give good yields and enantioselectivity.159... 

In determination of the absolute configuration of a-chiral primary amines, BINOL derivatives were used as chiral derivatizing agent.10 In this procedure, the chiral substrate was derivatized with R and S enantiomers of the 2,-methoxy-l,l -binaphthalene-8-carbaldehyde and the XH spectra of both diastereomers were compared. Comparison of the chemical shift differences of the diastereomers has allowed determination of the absolute configuration of the chiral substrate [5]. 

Enantioselective protonation of silyl enol ethers using a SnCl4-BINOL system has been developed (Scheme 83). 45 This Lewis-acid-assisted chiral Bronsted acid (LBA) is a highly effective chiral proton donor. In further studies, combined use of a catalytic amount of SnCl4, a BINOL derivative, and a stoichiometric amount of an achiral proton source is found to be effective for the reaction.346 347... 

The asymmetric hydrogenation of quinoline continues to be of interest. Li et al. reported the asymmetric hydrogenation of a variety of 2-substituted-quinolines to the corresponding tetrahydroquinolines using an Ir-catalyst with a BINOL-derived diphosphonite ligand... 

Woodward and co-workers utilized [Gu(MeCN)4]BF4 and (A)-BINOL-derived thiourethane ligand 87 in the addition reaction of trimethylaluminum to acyclic enones. Both yields and enantioselectivities were moderate (Scheme 44).130... 

The majority of the reported phosphoramidite ligands consist of BINOL and a diversity of readily available amines. Excellent enantioselectivities in the hydrogenation of a- and /fdehydroamirio acids, itaconates and enamides [63, 64] have been reported. In a recent full report, the group of Minnaard, De Vries and Fer-inga noted that especially the BINOL-derived ligands containing a piperidine or... 

In a comprehensive screen of the effect of TADDOL and BINOL-derived phosphites on the conjugate addition of diethylzinc to representative enones, Al-exakis et al. (181) revealed that the Feringa ligand exhibits the broadest scope, providing the conjugate adducts in selectivities ranging from 66 to 92% ee, Eq. 144. 

Yields and selectivities of BINOL-derived ligands in additions of Et2Zn and Me2Zn to 2-cyclohexenone are compiled in Tab. 7.2. 

Binol-derived phosphoroamidite PipPhos (19) has been successfully used as a ligand for the Ir-catalyzed asymmetric hydrogenation of 2- and 2,6-substituted quinolines [39], 2- and 2,6-substituted quinoxalines [40], and IV-aryl imines [41] (Fig. 16). 

Fig. 16 Summary of the best results obtained in the Ir-catalyzed hydrogenation of quinolines, quinoxalines, and Af-aryl imines using binol-derived phosphoroamidite PipPhos 19 ligand...

The chiral dialuminum Lewis acid 14, which is effective as an asymmetric Diels-Alder catalyst, has been prepared from DIBAH and BINOL derivatives (Scheme 12.12). " The catalytic activity of 14 is significantly greater than that of monoaluminum reagents. The catalyst achieves high reactivity and selectivity by an intramolecular interaction of two aluminum Lewis acids. Similarly, the chiral trialuminum Lewis acid 15 is quantitatively formed from optically pure 3-(2,4,6-triisopropylphenyl)binaphthol (2 equiv) and MeaAl (3 equiv) in CH2CI2 at room temperature (Scheme 12.12). " The novel structure of 15 has been ascertained by NMR spectroscopic analysis and measurement of the methane gas evolved. Trinuclear aluminum catalyst 15 is effective for the Diels-Alder reaction of methacrolein with cyclopentadiene. Diels-Alder adducts have been obtained in 99% yield with 92% exo selectivity. Under optimum reaction conditions, the... 

BINOL derivative SnCl4 complexes are useful not only as artificial cyclases but also as enantioselective protonation reagents for silyl enol ethers. " However, their exact structures have not been determined. SnCl4-free BINOL derivatives are... 

In 2008, Toste and coworkers reported the desymmetrization of me o-episulfonium ions 131 generated in situ from ring closure of sulfides 132 featuring a P-trichloro-acetimidate leaving group [76], Chiral BINOL-derived phosphoric acid (5)-3o (15 mol%, R = triggered the formation of the intermediate mera-epi-... 

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