BINOL derivatives addition with

Dixon reported that saturated BINOL 45 sufficiently activates various N-Boc aryl imines toward Mannich reaction with acetophenone-derived enamines to yield P-amrno aryl ketones in good yields and enantioselectivities (Scheme 5.62) [116]. The same group applied a BINOL-derived tetraol catalyst to the addition of meth-yleneaminopyrroHdine to N-Boc aryl imines. Interestingly, appendage of two extra diarymethanol groups to the BINOL scaffold resulted in a marked increase in enantiomeric excess [117]. 

Shibasaki and co-workers applied (BINOL)Al(III)-derived catalyst 5a, previously developed for the cyanation of aldehydes [28], to the asymmetric Strecker reaction. This catalyst proved to be highly enantioselective for both aromatic and a,p-unsaturated acyclic aldimines (>86% ee for most substrates) (Scheme 8) [63-65]. Aliphatic aldimines underwent cyanide addition with lower levels of enantioselectivity (70-80% ee). A significant distinction of 5 relative to other catalysts is, undoubtedly, its successful application to the hydrocyanation of quinolines and isoquinolines, followed by in situ protection of the sensitive cx-amino nitrile formed (this variant of the Strecker reaction is also known as the Reissert reaction [66]). Thus, Shibasaki has shown that high enantioselectivities (>80% ee for most substrates) and good yields are generally obtainable in the Reissert reaction catalyzed by 5b [67,68]. When applied to 1-substituted... 

Arai et al. also reported another BINOL-derived two-center phase-transfer catalyst 31 for an asymmetric Michael reaction (Scheme 6.11) [8b]. Based on the fact that BINOL and its derivatives are versatile chiral catalysts, and that bis-ammonium salts are expected to accelerate the reaction due to the two reaction sites - thus preventing an undesired reaction pathway - catalyst 31 was designed and synthesized from the di-MOM ether of (S)-BINOL in six steps. After optimization of the reaction conditions, the use of 1 mol% of catalyst 31a promoted the asymmetric Michael reaction of glycine Schiff base 8 to various Michael acceptors, with up to 75% ee. When catalyst 31b or 31c was used as a catalyst, a lower chemical yield and selectivity were obtained, indicating the importance of the interaction between tt-electrons of the aromatic rings in the catalyst and substrate. In addition, the amine moiety in catalyst 31 had an important role in enantioselectivity (34d and 34e lower yield and selectivity), while catalyst 31a gave the best results. 

A chiral Hg-BINOL derivative catalyses an efficient direct enantioselective addition of diphenylzinc to both aromatic and aliphatic aldehydes, with particularly good results for straight-chain cases.229 Aggregation phenomena in solution have been studied by NMR spectroscopy. 

A binol derivative (23) has allowed high enantioselectivities in the reaction of diphenylzinc with both aliphatic and aromatic aldehydes.105 Unlike other catalysts developed for the addition of diphenylzinc, the use of (23) avoids the need for additive and gives excellent results at room temperature. 

A similar system was studied a few years later by the S chaus group [89], who compared several binaphthol-derived chiral Bronsted acids such as 92a and 94a-d in the triethylphosphine-mediated MBH reaction between cyclohexenone and aldehydes. Optimized conditions were found with 2-20 mol% of chiral Bronsted acid and an excess of triethylphosphine (200 mol%) as the nucleophilic promoter at 0-10 °C in THF. Using PMe3 or P(n-Bu)3 in the reaction afforded 76 in yields similar to that of PEt3, but in lower enantioselectivity (50% and 64% ee, respectively). The use of only (R)-BINOL in the MBH reaction of dihydrocinnamaldehyde 74 and cyclohexenone 75 resulted in the formation of 76 in 16% ee. Partially saturated BINOL derivatives such as 94a-d offered high chemical yield and enantio selectivity (Scheme 5.19) [91]. Optimal results with the addition of aliphatic al-... 

Diphenyl-BINOL-derived chiral aluminum reagents are prepared in situ by addition of Ethylaluminum Dichloride or Diethylaluminum Chloride to 3,3 -diphenyl-BINOL. These chiral aluminum reagents promote the enantioselective Diels-Alder reaction of cyclopentadiene with the oxazolidone dienophile (eq 14). Endo products are obtained with a high level of asymmetric induction (>90% ee) however, a stoichiometric amount of the Lewis acid is required. The preparation and use of a C3 symmetric BINOL-derived boronate has been reported (eq 15). BINOL-B(OAr)3 complexes have recently been developed for the asymmetric Diels-Alder reaction with imines (eq 16). ... 

Carreira employed a chiral BINOL-derived Schiff base-titanium complex as a catalyst for aldol reactions with acetate-derived ketene silyl acetals (Sch. 38) [100]. The catalyst was prepared in toluene in the presence of salicylic acid, which was reported to be crucial to achieving high enantioselectivity. A similar Schiff base-titanium complex is also applicable to the carbonyl-ene type reaction with 2-methoxypropene (Sch. 39) [101]. Although conducting the reaction in toluene or ether solution provided no addition product, excellent chemical yield and enantioselectivity were attained by the use of 2-methoxypropene as a solvent. 

Trimethylsilyloxy)furan can also be used as a functionalized silyl enol ether for the asymmetric catalytic aldol-type reaction. Figadere has reported that the reaction of aliphatic aldehydes with the siloxyfuran catalyzed by BINOL-derived titanium complex provides the diastereomeric mixtures with high enantioselectivity (Sch. 42) [107], The addition reaction proceeds at the y position of the siloxyfuran to give butenolides of biological and synthetic importance. 

Oguni has reported asymmetric amplification [12] ((-i-)-NLE) in an asymmetric carbonyl addition reaction of dialkylzinc reagents catalyzed by chiral ami-noalcohols such as l-piperidino-3,3-dimethyl-2-butanol (PDB) (Eq. (7.1)) [13]. Noyori et al. have reported a highly efficient aminoalcohol catalyst, 2S)-3-exo-(dimethylamino)isobomeol (DAIB) [14] and a beautiful investigation of asymmetric amplification in view of the stability and lower catalytic activity of the het-ero-chiral dimer of the zinc aminoalcohol catalyst than the homo-chiral dimer (Fig. 7-5). We have reported a positive non-linear effect in a carbonyl-ene reaction [15] with glyoxylate catalyzed by binaphthol (binol)-derived chiral titanium complex (Eq. (7.2)) [10]. Bolm has also reported (-i-)-NLE in the 1,4-addition reaction of dialkylzinc by the catalysis of nickel complex with pyridyl alcohols [16]. 

Few examples have been reported demonstrating enantioselective cyclization methodology. One known example, however, is similar to the diastereoselective cyclization of 175, which uses a menthol-derived chiral auxiliary and a bulky aluminum Lewis acid (see Eq. (13.55)). The enantioselective variant simply utilizes an achiral template 188 in conjunction with a bulky chiral binol-derived aluminum Lewis acid 189 (Eq. (13.59)) [75]. Once again the steric bulk of the chiral aluminum Lewis acid complex favors the s-trans rotamer of the acceptor olefin. Facial selectivity of the radical addition can then be controlled by the chiral Lewis acid. The highest selectivity (48% ee) was achieved with 4 equivalents of chiral Lewis acid, providing a yield of 63%. 

In 1988, Mukaiyama et al. reported the Sn(OTf)2-50d-catalyzed asymmetric Michael reaction of a trimethylsilyl enethiolate, CH2=C(SMe)SSiMej (up to 70% ee) [243]. It was proposed that the catalytic reaction proceeded via an Sn(II) enethiolate. They also demonstrated that a BINOL-derived oxotitaniurn catalyzes the Michael addition of ketene silyl thioacetals to a-enone with high enantioselectivity (up to 90% ee) [244]. After this pioneering work other research groups developed new reaction systems for enantioselective Mukaiyama-Michael reactions. 

Sasai developed miceUe-derived polymer-supported catalysts for a variety of enantioselective reactions, including diethylzinc addition [18]. The surfactant monomer 20 having tetraethylene glycol chains formed micelles in water and, followed by copolymerization with styrene, gave the spherical polymer. A coupling reaction of the polymer with a BINOL derivative and deprotection of the methoxymethyl groups of the BINOL moiety afforded the desired chiral polymer 21, as shown in Scheme 3.5. The catalytic asymmetric ethylation of benzaldehyde was... 

Reetz and Li studied asymmetric hydrogenation of quinolines using iridium complex with a chiral BINOL derived diphosphonite ligand with an achiral diphenyl ether backbone as catalyst, achiral P ligands serving as possible additives (Scheme 10.7) [9]. Under the optimized conditions, 2 substituted and... 

In 2008, Vries group reported asymmetric hydrogenation of quinolines catalyzed by iridium complexes based on monodentate BINOL derived phos phoramidites PipPhos. They used tri ortho tolylphosphine and/or chloride salts as additives, and enantioselectivities were strongly enhanced to 89% ee (Scheme 10.13) [17]. Toluene and DCM were the best solvents, and the reaction was carried out at 60°C for 24h in the pressure of 50 bar H2, and a series of 2 substituted and 2,6 disubstituted quinolines were examined with excellent... 

Compared to the result with LLB, the use of a 6,6 -dibromosubstituted BINOL derived LLB type catalyst LLB led to significantly improved yield, endo exo ratio and enantioselectivity (86% ee). Interestingly, the addition of 12-crown-4 to the reaction medium resulted in the formation of the adduct 49 with much lower enantiomeric excess. This result appears to suggest that the lithium cation(s) play a key role in activation of the dienophile. 

Feng developed an enantioselective Strecker-type reaction of ketimines with trimethylsilylcyanide catalysed by a chiral BINOL-derived sodium phosphate (10 mol%) prepared in situ from 55 and NaH (Scheme 2.35). As a protic additive, 10 mol% of 4-tert-butyl-2-adamantylphenol (56) was effective for improving the yield and enantioselectivity. Both aliphatic and aromatic ketimines, including cyclic ketimines derived from a-indanone and a-tetralone, were used for this reaction. 

Chen developed a catalytic enantioselective Michael addition of trimethylsilylcyanide to chalcones by using chiral 3,3 -(l-adamanthyl)2-BINOL-derived sodium phosphate, which was prepared in situ from 57 and NaOH, in the presence of 2-fert-butylphenol (Scheme 2.36). The reactions proceeded at 78 °C within 3 h, and the corresponding p-cyano ketones were obtained in high yields with moderate enantioselectivities (up to 72% ee). 

In 2003, we first demonstrated that l,l -bi-2,2 -naphthol (BINOL)-derived chiral LBBA (Lewis base and Bronsted add) bifunctional phosphine CP17 (LB = PPhs, BA = Ph-OH) could be used as an effective catalyst in asymmetric aza-MBH reaction of A-tosylimines with MVK and phenyl acrylate, affording the corresponding adducts in good yields with high ees (Scheme 2.119). The addition of molecular sieves increased chemical yields because they removed the ambient moisture that caused the decomposition of A-sulfonated imines. The asymmetric induction of this catalyst is comparable to that of the quinidine... 

---