A New and Practical Method for Preparing Enantiomerically Pure [1,1′‐Binaphthalene]‐2,2′‐diol: Resolution of Racemic [1,1′‐Binaphthalene]‐2,2′‐diol with threo ‐(1 S ,2 S )‐2‐Amino‐1‐(4‐nitrophenyl)propane‐1,3‐diolCyclohexanone Condensate

An economic and practical method for preparing enantiomerically pure [1,1′‐binaphthalene]‐2,2′‐diols is reported. Thus, a condensate of threo ‐(1 S ,2 S )‐2‐amino‐1‐(4‐nitrophenyl)propane‐1,3‐diol and cyclohexanone (CHANP) was used as a resolving agent. A 2 : 1 : 1 mixture of racemic [1,1′‐binaphthalene]‐2,2′‐diol, boric acid, and CHANP was refluxed for several hours in THF or MeCN to give a white precipitate of bis{( R )‐[1,1′‐binaphthalene]‐2,2′‐diol}boric acid CHANP derivative, from the precipitate, and a filtrate separated from the precipitate, ( R )‐ and ( S )‐[1,1′‐binaphthalene]‐2,2′‐diol of 100% ee were obtained in ca. 65% yield, respectively.