Unexpected Formation of a Chiral spiro-System in the Reaction of the Dilithium Derivative of Hexafluorocumyl Alcohol with N-(t-Butylsulfenyl)phthalimide.

Abstract

An unexpected course of the reaction of hexafluorocumyl alcohol dilithium derivative 2 with N-(t-butylsulfenyl)phthalimide (3) has been presented. The process proceeded under mild conditions and resulted in previously undescribed chiral spiro-system - 3',3'-bis(trifluoromethyl)-3H,3'H-1,1'-spirobis(isobenzofuran)-3-one (5) as the only product. A detailed spectral analysis of the product has been provided, and mechanistic aspects have been investigated. Attempts to separate the enantiomers of compound 5 using a semipreparative HPLC method with a chiral stationary phase column have been described. The repeatability of the reaction using analogs of alcohol 4 has also been tested. DFT calculations of absolute configuration assignment have been performed successfully.