1,1 -Binaphthalene-2,2 -diol complexes

The l,T-binaphthalene-2,2 -diol complexes of Lewis acids have received considerably more attention. Mikami hrst reported the apphcation of BtNOL/ri(IV) complexes for enantioselective allylations of glyoxylates.ii Keck" and Umani-Ronchi/Tagliavinin independently devised allylation procedures with (/ )-BtN0L/Ti(0-iPr)4 and (5)-BIN0L/Ti(0-iPr)2Cl2, respectively (Scheme 5.2.83). The use of molecular sieves is essential for high reactivity and stereoselectivity. 

Binaphthalene-2,2 -diol-gallium/IM 2-Aryloxy alcohols. meso-Epoxidc Ga—Li linked BINOL complex with high... 

The modification by-passes the use of molecular sieves, often recommended by other authors, and is claimed to improve the reproducibility of the reaction. In a Schlenk tube, 2 mL of degassed toluene was added to 60 mg (0.2 mmol) of (i )-l,r-binaphthalene-2,2 -diol, then 59 pL (0.20 mmol) of titanium isopropoxide was added. After stirring for 1 hour, the solvent was removed. These complexes are not air stable and were stored in Schlenk tubes under Argon. For the catalytic allylation reactions the complexes were prepared just before use. 

Copper(II) amine complexes are very effective catalysts for the oxidative coupling of 2-naphthols to give symmetrical l,F-binaphthalene-2,2 -diols. Recent work has extended this methodology to the cross-coupling of various substituted 2-naphthols. For example, 2-naphthol and 3-methoxycarbonyl-2-naphthol are coupled under strictly anaerobic conditions using CuCU/tert-butylamine in methanol to give the unsymmetrical bi-naphthol in 86% yield (eq 20). 

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