Bis- 3-naphthol

Triflates of phenols are carbonylated to form aromatic esters by using PhjP[328]. The reaction is 500 times faster if dppp is used[329]. This reaction is a good preparative method for benzoates from phenols and naphthoates (473) from naphthols. Carbonylation of the bis-triflate of axially chiral 1,1 -binaphthyl-2,2 -diol (474) using dppp was claimed to give the monocarboxy-late 475(330]. However, the optically pure dicarboxylate 476 is obtained under similar conditions[331]. The use of 4.4 equiv. of a hindered amine (ethyldiisopropylamine) is crucial for the dicarbonylation. The use of more or less than 4.4 equiv. of the amine gives the monoester 475. 

R)-(+)-1,1 -Bi-2-naphthol is purchased from Wako Pure Chemical Industries Ltd. or Aldrich Chemical Company, Inc. 

Catalyst 329, prepared from trimethylaluminum and 3,3/-bis(triphenylsily 1)-1,1 /-bi-2-naphthol, allowed the preparation of the endo cycloadduct (2S )-327 with 67% ee. The use of non-polar solvents raised the ee, but lowered the chemical yield213. Recently, it was reported that the reaction to form 327 exhibited autoinduction when mediated by catalyst 326214. This was attributed to a co-operative interaction of the cycloadduct with the catalyst, generating a more selective catalytic species. A wide variety of carbonyl ligands were tested for their co-operative effect on enantioselectivity. Sterically crowded aldehydes such as pivaldehyde provided the best results. Surprisingly, 1,3-dicarbonyl compounds were even more effective than monocarbonyl compounds. The asymmetric induction increased from 82 to 92% ee when di(l-adamantyl)-2,2-dimethylmalonate was added while at the same time the reaction temperature was allowed to increase by 80 °C, from -80 °C to 0°C. 

Figure 7.13 1,1 -Bi-2-naphthol (BINOL) can dramatically enhance proline-catalyzed aldol reactions.

B. A 500-mL, two-necked, round-bottomed flask is equipped with a Teflon-coated magnetic stirring bar (Note 1), condenser, rubber septum and nitrogen inlet. The flask is charged with a suspension of lithium aluminum hydride (UAIH4) powder (2.13 g, 53.4 mmol) in 110 mL of anhydrous THF. The suspension is stirred at room temperature and a solution of ethanol (EtOH) (3.13 mL, 53.4 mmol, Note 7) in 10 mL of THF is added dropwise over a period of 15 min with vigorous evolution of hydrogen gas. The mixture is stirred for 20 min and a solution of (R)-1,1 -bi-2-naphthol (16.0 g,... 

R)-1,1 -Bi-2-naphthol was prepared by resolution employing the N-benzylammonium chloride salt of (-)-cinchonidine to form separable diastereomeric clathrate complexes. Hu, Q-S. Vitharama, D. Pu, L. Tetrahedron Asymmetry 1995, 6, 2123. 

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