A brief overview is presented of the field of organocatalysis using chiral H‐bond donors, chiral Brønsted acids, and chiral counter‐anions (Fig. 1). The role of TADDOLs (=α,α,α′,α′‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanols) as H‐bond donors and the importance of an intramolecular H‐bond for acidity enhancement are discussed. Crystal structures of TADDOLs and of their N‐, S‐, and P‐analogs (Figs. 2 and 3) point the way to proposals of mechanistic models for the action of TADDOLs as organocatalysts (Scheme 1). Simple experimental two‐step procedures for the preparation of the hitherto strongest known TADDOL‐derived acids, the bicyclic phosphoric acids (2 in Scheme 2) and of a phosphoric‐trifluorosulfonic imide (9 in Scheme 4), are disclosed. The mechanism of sulfinamide formation in reactions of TADDAMIN with trifluoro‐sulfonylating reagents is discussed (Scheme 3). pKa Measurements of TADDOLs and analogs in DMSO (reported in the literature; Fig. 5) and in MeO(CH2)2OH/H2O (described herein; Fig. 6) provide information about further possible applications of this type of compounds as strong chiral Brønsted acids in organocatalysis.

TADDOL (=α,α,α′,α′‐Tetraaryl‐1,3‐dioxolane‐4,5‐dimethanol) and the corresponding dichloride are converted to TADDAMINs (=(4S,5S)‐2,2,N,N′‐tetramethyl‐α,α,α′,α′‐tetraphenyl‐1,3‐dioxolan‐4,5‐dimethanamines) (Scheme 2) and ureas, 12–15, and to TADDOP derivatives with seven‐membered OPO ester rings (Schemes 3 and 4). Cl/P‐Replacement via the MichaelisArbuzov reaction (Scheme 7) on mono‐ and dichlorides, derived from TADDOL, are described. It was not possible to obtain phosphines with the P‐atom attached to the benzhydrylic C‐atom of the TADDOL skeleton (Schemes 6 and 7). The X‐ray crystal structures (Figs. 1 and 2) of ten of the more than 30 new TADDOL derivatives are discussed. Full experimental details are presented.

A brief overview is given involving the role of TADDOLs as H‐bond donors and the importance of an intramolecular H‐bond for acidity enhancement.