1 ’-hydroxy-1- binaphthyl

Figure 4.23 Synthesis of a hydroxy-binaphthyl functionalised imidazolium salt and its...

The protocol leading to the unsaturated 1,1 -hydroxy-binaphthyl saturated NHC was a chance discovery, enabled by an aqueous workup procedure. The yield is only moderate (40%) and has to be separated from the main product, the targeted bis-imidazolium salt (51%). A better synthesis for this ligand might be desirable, although the saturated NHC equivalent is readily available [18,86,88,89]. 

The hydroxy-binaphthyl functionalised saturated imidazolium salt is readily available from 1-amino-I -hydroxy-binaphthyl in a reaction with a ( oc-protected mesitylamine aldehyde [86] (see Figure 4.24). The resulting Schiff base is reduced to the diamine by Na(OAc)3BH. Subsequent deprotection and ring closure reaction with triethyl orthoformate yields the corresponding hydroxy-binaphthyl functionalised saturated imidazolium salt. Reaction with silver(I) carbonate and subsequent carbene transfer to the ruthenium(II) precursor yields the asymmetric olefin metathesis precatalyst. 

This research group also investigated the intramolecular arene epoxidation of binaphthyl phosphine derivatives. Singlet oxygen reacts with l,l -binaphthyl-2-di-tert-butylphosphine to form the corresponding phosphine oxide-epoxide intermediate with complete retention of stereochemistry. This then undergoes a slow NIH-rearrangement to form the 1-phosphinoxido-l -hydroxy binaphthyl derivative (Scheme 9). °... 

Additional lack of chain flexibility is introduced in the polyphosphazene skeleton when polyspirophosphazenes are considered. These materials are obtained by reacting 2,2 -di-hydroxy biphenyl or l,r-binaphthyl derivatives with polydichlorophosphazene [305], leading to the formation of polymers having the structure shown in Formula below. 

In 2000, Woodward et al. reported that LiGaH4, in combination with the S/ 0-chelate, 2-hydroxy-2 -mercapto-1,1 -binaphthyl (MTBH2), formed an active catalyst for the asymmetric reduction of prochiral ketones with catecholborane as the hydride source (Scheme 10.65). The enantioface differentiation was on the basis of the steric requirements of the ketone substituents. Aryl w-alkyl ketones were reduced in enantioselectivities of 90-93% ee, whereas alkyl methyl ketones e.g. i-Pr, Cy, t-Bu) gave lower enantioselectivities of 60-72% ee. 

Recently, catalytic asymmetric Diels-Alder reactions have been investigated. Yamamoto reported a Bronsted-acid-assistcd chiral (BLA) Lewis acid, prepared from (R)-3-(2-hydroxy-3-phcnylphenyl)-2,2 -dihydroxy-1,1 -binaphthyl and 3,5A(trifluoromethy I) - be nzeneboronic acid, that is effective in catalyzing the enantioselective Diels-Alder reaction between a,(3-enals and various dienes.62 The interesting aspect is the role of water, THF, and MS 4A in the preparation of the catalyst (Eq. 12.19). To prevent the trimerization of the boronic acid during the preparation of the catalyst, the chiral triol and the boronic acid were mixed under aqueous conditions and then dried. Using the catalyst prepared in this manner, a 99% ee was obtained in the Diels-Alder reaction... 

Park et al.34,35 have used (S)-2-hydroxy-2 -(3-phenyl-uryl-benzyl)-l,l -binaphthyl-3-carboxaldehyde for conversion of L-amino acids or peptides into D-amino acids [17]. 

R)-(-)-Methyl 3-hydroxybutanoate Butyric acid, 3-hydroxy-, methyl ester, D-(-)-(8) Butanoic acid, 3-hydroxy- methyl ester, (R)- (9) (3976-69-0) [(R)-2,2 -Bls(dlphenylphosphino)-1,1 -binaphthyl]dichlororuthenium Ruthenium, [[1,1 -binaphthalene]-2,2 -diylbis(diphenylphosphine)-P,P ]dichloro- (12) (115245-70-0)... 

Diastereoselectivity in the aldol and the conjugate additions of 2 -hydroxy-1,T-binaphthyl ester enolates with a variety of carbonyl electrophiles has also been explored the tendency of the ester enolates, generated by BuLi, to react with aldehydes to give threo products preferentially with high diastereoselectivity has been interpreted in terms of an acyclic transition state of chelated lithium enolate involving the aldehyde carbonyl and the 2 -hydroxy group. 

Oxybis[2-(ethyleneoxy)-2 -hydroxy-1,1 -binaphthyl] (2.32 g, 3.61 mmol) and potassium carbonate (l.lOg, 7.96mmol) were placed in a 300mL round-bottomed flask equipped with a reflux condenser and a magnetic stirrer bar. Dry methyl ethyl ketone (142 mL) was then added and the mixture was refluxed on an oil bath for 1 h. To this solution, Af,Af-bis-(2-p-nitrobenzenesulfonyloxyethyl)-A -p-nitrobenzenesulfonamide dichloromethane complex (3.44g, 4.32 mmol) was added. 

ASYMMETRIC REDUCTIONS 2,2 -Di-hydroxy-1,1 -binaphthyl-Eithium aluminum hydride. (2S,3RH+)-4-Dimethyl-ainino-3-methyl-l, 2-diphenyl-2-butanol. Lithium aluminum hydride-(-)-N-Methylephedrine. B-(3)-a-Pinanyl-9-borabicyclo[3.3.11nonane. (S)-2-(2.6-Xylidinomethyl)pyrrolidine. 

Lithium borohydride, 92 (lR,2S)-N-Methylephedrine-0-pro-pionate, 308 Norephedrine, 200 2-Oxazolidones, chiral, 225 (2R,4R)-Pentanediol, 237 Potassium triethylborohydride, 260 Other hydroxy carbonyl compounds (R)-( + )- and (S)-( - )-2,2 -Bis-(diphenylphosphine)-1,1 -binaphthyl, 36 Ketones... 

Keywords 2-amino-2 -hydroxy-3,-(methoxycarbonyl)-l,l -binaphthyl, SN2 substitution, 2-metliy lamino-2 -hydroxy-3 -carboxy-1,1 -binaphthyl... 

A related approach has recently been reported by Belokon and Kagan et al. These workers used chiral TADDOL-type diols, derived from tartaric acid and 2-amino-2 -hydroxy-1,1 -binaphthyl (NOBIN), as catalysts to obtain yields of up to 95% and enantioselectivity up to 93% ee [59-61], The catalytically active species seem to be the sodium salts of the diols. 

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