1‐Arylfluorenols: Convenient preparation via the ester‐mediated nucleophilic aromatic substitution protocol, facile racemization, and intrinsic chiral induction ability

Novel 1‐aryl‐9 H ‐fluoren‐9‐ols 1 were conveniently synthesized by using the ester‐mediated nucleophilic aromatic substitution on 2,6‐dimethoxybenzoate 2 by aryl Grignard reagents as the key step. Racemic 1‐phenylfluorenol 1a was converted to the diastereomeric esters 8 of ( S )‐2′‐methoxy‐1,1′‐binaphthyl‐2‐carboxylic acid, which were readily separable by silica‐gel column chromatography. Reduction of the optically pure diastereomer (+)‐8 with LiAlH 4 accompanied an appreciable racemization to give (+)‐1a of 89% ee, which provides the first isolation of an optically active fluorenol of defined enantiomeric purity. Intrinsic chiral induction abilities of the 9‐fluorenols 1 were examined in the atrolactic acid synthesis from phenylglyoxylates 9 and methylmagnesium iodide with diastereoselectivity of up to 85% de and the binaphthyl coupling of 1‐methoxy‐2‐naphthoates 11 with 2‐methoxy‐1‐naphthylmagnesium bromide with up to 73% de. Chirality 10:619–626, 1998. © 1998 Wiley‐Liss, Inc.