Preparation of TADOOH,a Hydroperoxide from TADDOL,and Use in Highly Enantioface‐ and Enantiomer‐Differentiating Oxidations

Replacement of one OH group in TADDOL (=α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanol) by an OOH group gives a stable, crystalline chiral hydroperoxy alcohol TADOOH (={(4R,5R)‐5‐(hydroperoxydiphenyl)methyl]‐2,2‐dimethyl‐1,3‐dioxolan‐4‐yl}diphenylmethanol) 3 , the crystal structure of which resembles those of numerous other TADDOL derivatives (Fig. 2). The new hydroperoxide was tested as chiral oxidant in three types of reactions: the epoxidation of enones with base catalysis (Scheme 2), the sulfoxidation of methyl phenyl sulfide (Scheme 3), and the Baeyer‐Villiger oxidation of bicyclic and tricyclic cyclobutanones, rac‐ 10a – d with kinetic resolution (Scheme 4, Fig. 3, and Table). Products of up to 99% enantiomer puritiy were isolated (the highest values yet observed for oxidations with a chiral hydroperoxide!). Mechanistic models are proposed for the stereochemical courses of the three types of reactions (Schemes 5 and 6, and Fig. 4). Results of AM1 calculations of the relative transition‐state energies for the anionic rearrangements of the exo Criegee adducts of TADOOH to the enantiomeric bicyclo3.2.0]heptan‐6‐ones are in qualitative agreement with the observed relative rates (Table and Fig. 5).