2-naphthol derivatives BINOL

Chiral metal alkoxides M(OR)4 have been developed as asymmetric variants of ordinary Lewis acids, such as A1C13 and ZrCU, and are used as catalysts for selective carbon-carbon bond formation. Thus, starting from bidentate l,l -bi-2-naphthol derivatives (BINOL) and SnCU, a series of chiral tin(iv) aryloxides 221 (Figure 7) was prepared and successfully applied to the enantioselective Diels-Alder reaction <2006TL873>. Similar silocanes obtained from menthone- or camphor-derived 2,2 -biphenols have been obtained and their configuration was analyzed by NOE differential spectroscopy (NOEDS) <1997JOC7156>. 

The reaction between epoxides and ammonia is a general and useful method for the preparation of P-hydroxyamines. " Ammonia gives largely the primary amine, but also some secondary and tertiary amines. The useful solvents, the ethanolamines, are prepared by this reaction. For another way of accomplishing this conversion, see 10-54. The reaction can be catalyzed with Yb(OTf)3 and in the presence of a-BINOL is l,l -bi-2-naphthol derivative gives amino alcohols with high asymmetric induction. A variation used Yb(OTf)3 at lOkbar or at ambient pressure. Lithium triflate can also be used. Primary and secondary amines give, respectively, secondary and tertiary amines, for example. 

Scheme 16. Comparison of TADDOL with BINOL and Future Goals. Derivatives of (R,R)-TADDOLs and of (P)- or (S)-BINOL, when employed in the same reaction, often give the same product enantiomer preferentially (cf. the Cj-symmetrical structural similarity). While TADDOLs are much easier to prepare and to modify, they are many orders of magnitude less acidic than BINOLs (TADDOLates are less polar ligands to a metal). Some TADDOL derivatives contain CPh2X groups which are labile to (undesired) nucleophilic substitution the dioxolane group of TADDOLs, on the other hand, is surprisingly stable to hydrolysis. BINOL (a naphthol derivative ) can be very sensitive to oxidation and (undesired) electrophilic aromatic substitution, and there are conditions under which it may racemize. Some goals to increase the usefulness of the TADDOL system are shown at the bottom of the Scheme other P derivatives, more acidic derivatives, reagents for enantioselective protonation, deprotonation,...

Besides, it was disclosed that complex (S, Ra)-28 derived from Hg-BINOL is another highly efficient catalyst for the oxidative coupling of 2-naphthol derivatives. An attractive feature of this catalyst is that air (1 atm) can be used as the oxidant for a series of substrates with substitution at the C6 or C7 positions of the naphthalene ring, and the reaction time can also be shortened to 1.5 to 2 days (Table 3.9). 

Apparently, much higher yields can be achieved in the oxidative coupling of 2-naphthol derivatives by means of Fe(III), Cu(I), Cu(ll), Mn(III), or Ti(IV) salts (Scheme 2.66) [27]. These reactions usually proceed very fast. Partially 0-protected binaphthols can be obtained by monoetherification of one hydroxy group via a modified Mitsunobu reaction [28]. Several methods allow the kinetic resolution of racemic atropisomers and, hence, access to optically pure (R)- or (S) binaphthol (BINOL) [27]. 

Some cyclobutanones were amenable to asymmetric reaction, in which a BINOL (l,l -bi-2-naphthol)-derived phosphoramidite worked as an excellent... 

Using 1 equivalent aluminum Lewis acid (14) derived from (R)-l,l -bi-2-naphthol ((R) BINOL) and dimethylaluminum chloride, reaction of N,N-dimethy-laniline with 2-pyridinecarboxaldehyde in dichloromethane at 20 afforded the para- substituted alcohol in 63% yield with 43% ee as shown in Scheme 6.16. 

The ability of chiral binaphthol (BINOL) derivatives as a Br0nsted acid catalyst to facilitate asymmetric transformations was demonstrated by Schaus by the development of the highly enantioselective Morita-Baylis-Hilhnan reaction of cyclohex-enone with aldehydes effectively catalyzed by (R)-octahydro-l,l -bi-2-naphthol derivatives, bearing either 3,5-bis(trifluoromethyl)phenyl (24a) or 3,5-xylyl (24b) groups at the 3,3 -positions, in combined use with triethylphosphine as a nucleophilic promoter (Scheme 7.43) [68]. 

Naphthol is another electron-rich aromatic compound which can also lead to sp -sp CDC-type products. Thus, a new type of Betti base was formed via the CDC reaction of N-phenyl-THIQ with 2-naphthol derivatives under our CuBr/TBHP system with a small amount of homocoupled 2,2-binaphthol (BINOL) (Scheme 1.10). Subsequently, the scope of cross-dehydrogenative Friedel-Crafts type aiylations was significantly improved by the development of highly efficient catalyst systems, and an intramolecular Cu-catalyzed aerobic synthesis of functionalized cinnolines via a Friedel-Crafts-type CDC aiylation was reported by Zhang et al. ... 

A heterobimetallic BINOL-Ga/Li complex 53 has been developed for the enantioselective ARO of meso-cpoxides (BINOL = l,T-bi(2-naphthol)).278 Using />-methoxyphenol as the nucleophile, this etherification reaction was observed to take place with a high level of asymmetric induction. An improved catalyst 54 has also been reported that exhibits greater stability under the reaction conditions and delivers higher yields and ee s (Equation (78)).279 A simple catalyst derived from Sc(OTf)3 and the chiral bipyridine ligand 52 has been shown to be effective for the ARO of aryl-substituted /// -epoxides with aliphatic alcohols to give high ee s (Equation (79)).280... 

BINOL and its derivatives have been utilized as versatile chiral sources for asymmetric catalysis, and efficient catalysts for their syntheses are, ultimately, required in many chemical fields [39-42]. The oxidative coupling of 2-naphthols is a direct synthesis of BINOL derivatives [43, 44], and some transition metals such as copper [45, 46], iron [46, 47] and manganese [48] are known as active metals for the reaction. However, few studies on homogeneous metal complexes have been reported for the asymmetric coupling of 2-naphthols [49-56]. The chiral self-dimerized V dimers on Si02 is the first heterogeneous catalyst for the asymmetric oxidative coupling of 2-naphthol. 

Stereoselective chelate-controlled addition of Grignard reagents to tetrahydrooxepine derivatives (Equation 3) involves Zr-catalyzed kinetic resolution with (i )-[EBTHI]Zr-BINOL (BINOL= l,l -bi-2-naphthol) <1996JA4291, 1997JA6205, 1999JOC854>. 

Pyridinecarbaldehyde reacts with trimethylsilyl cyanide in the presence of the catalysts derived from either enantiomer of 3,3 -bis(diethylaminomethyl)-substituted binaphthol or 1,1 -bi-2-naphthol (BINOL) and... 

In the reaction of 1-naphthoxide ions, a mixture of 2- and 4-aryl-, along with 2,4-diaryl-l-naphthol, is formed. However, substitution occurs only at C4 with the 2-Me-substituted anion (50-70% yields) [1[. On the other hand, 2-naphthoxide ions react with ArX to give substitution only at Cj of the naphthalene ring [32, 33]. The reactivity of the 2-naphthoxide ions allows the synthesis of naphthylpyridines, naphthylquinolines, and naphthylisoquinolines via their coupling reactions with the corresponding halo arenes, in good to excellent yields (50-95%) [33], The photostimulated reaction between 2-naphthoxide ions and l-iodo-2-methoxy-naphthalene was explored in liquid ammonia, as a novel approach to the synthesis of [1,1 ] binaphthalenyl-2,2 -diol (BINOL) derivatives (Scheme 10.23). This procedure has also been applied to the synthesis of BINOL in moderate yield (40%), which represents the first report of an SRN1 reaction in water [34]. 

Nomacemic binaphthol (BINOL) ligands are heavily utilized in asymmetric synthesis. They can be readily fashioned from 2-naphthol precursors employing Cu(I) or Cu(ll) salts. With either an external source of chirality (e.g. 1,5-diaza-cfr-decalin, l),ii or an internal chiral center (e.g. as in the proline-derived amide 2), derivatives substituted at the key 3- and 3 -sites are realized under mild conditions with ee s (see Enantioselectivity) up to 94%. 

A general review of the advances in homogeneous and heterogeneous catalytic asymmetric epoxidation covering Sharpless, porphyrin, A, A -bis(saclicylaldehydo)ethylenediamine (salen), and l,T-bi-2-naphthol (BINOL) systems, carbonyl-derived dioxiranes and iminium species, as well as their supported counterparts, has recently been published <2005CRV1603>. 

In this chapter, we focus on recent achievements in the enantioselective synthesis of chiral amines using 1,1 bi 2 naphthol (BINOL) derived monophosphoric acid (1) or related phosphoric acids as chiral Bronsted acid catalysts 2, 3], The contents are arranged according to the type of bond forming reaction, including carbon carbon, carbon hydrogen, and carbon heteroatom bond forming reactions, followed by specific reaction types. 

As indicated by Miyano, alkali metal phenoxides derived from (R)-l,l -bi-2-naphthol (BINOL) possessing an oligoether moiety promoted the asymmetric addition of ketoesters to 7 [39]. Simple BINOL or its monomethyl derivative gave the racemic product, and the appropriate length of the polyoxyethylene chain... 

In the previous section, lanthanide triflates were shown to be excellent catalysts for achiral aza Diels-Alder reactions. While stoichiometric amounts of Lewis acids are required in many cases, a small amount of the triflate effectively catalyzes the reactions. On the other hand, chiral lanthanide Lewis acids have been developed to realize highly enantioselective Diels-Alder reactions of 2-ox-azolidin-l-one with dienes [89]. The reaction of N-benzylideneaniline with cyclop entadiene was first performed under the influence of 20 mol% of a chiral ytterbium Lewis acid prepared from ytterbium triflate (Yb(OTf)3), fR)-(+)-l,l -bi-naphthol (BINOL), and trimethylpiperidine (TMP). The reaction proceeded smoothly at room temperature to afford the desired tetrahydroquinoline derivative in a 53% yield, although no chiral induction was observed. At this stage, it was indicated that bidentate coordination between a substrate and a chiral Lewis acid would be necessary for reasonable chiral induction. N-Benzylidene-2-hydroxy aniline (31a) was then prepared, and the reaction with cyclopentadiene (32a) was examined. It was found that the reaction proceeded smoothly to afford the corresponding 8-hydroxyquinoline derivative (33a) [90] in a high yield. The enantiomeric excess of the cis adduct in the first trial was only 6% however, the selectivity increased when diazabicyclo-[5,4,0]-undec-7-ene (DBU) was used in-... 

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