1,3-Dioxolane-4,5-dimethanol

Seebach, D., Hayakawa, M., Sakaki, J. and Schweizer, W.B. (1993) Derivatives of tetraaryl-2,2-dimethyl-1,3 -dioxolane-4,5 -dimethanol (TADDOL) containing nitrogen, sulfur, and phosphorus atoms. New ligands and auxiliaries for enantioselective reactions. Tetrahedron, 49, 1711-1724. 

Ft,R)-2,2-Dimethyl-a,a,a ,a -te1ra(naphth-2--yl)-1,3-dioxolane-4,5-dimethanol from Dimethyl Tartrate and 2-Naphthylmagnesium Bromide. 

Analysis of Reagent Purity H NMR and C NMR (CD2Cl2). Preparative Methods it can be prepared in two steps from either (4/f,trtins)-2,2-dimethyl-a,a,a, a -tetraphenyl-1,3-dioxo-lane-4,5-dimethanol (R,R-Taddol) or (45,trans)-2,2-dimethyl-a,a,a, a -tetraphenyl-1,3-dioxolane-4,5-dimethanol (5,5-Tad-dol) (eq 1). ... 

A newer approach toward the enantioselective electrophilic fluorination of jS-ketoesters is based on enolization of the substrate under neutral conditions by coordination to a chiral titanium catalyst [211]. The catalyst, a chiral titanium TADDOLato complex (TADDOL = a,a,a, a -tetraaryl-2,2-dimethyl-1,3-dioxolan-4,5-dimethanol) [212, 213], coordinates to the -ketoester, enolizes it, and thus renders it susceptible to electrophilic fluorination (Scheme 2.95). One face of the prochiral enolate substructure is covered by a bulky naphthyl substituent from the TADDOL ligand, impeding electrophilic attack of F-TEDA. 

DIMETHANOL [1,3-DIOXOLANE-4,5-DIMETHANOL, 2,2-DIMETHYL-a,a,a, a -TETRA-2-NAPHTHALENYL-, (4R-trans)-] (137365-09-4),... 

C. (4R,5R)-2,2-Dimethyl-a,a,a, a -tetra(naphth-2-yl)-1,3-dioxolane-4,5-dimethanol. To the Grignard solution obtained in Part B is added, with stirring and cooling by an ice bath, a solution of (R.R)-dimethyl O.O-isopropylidenetartrate (48.1 g, 0.22 mol) (see Part A) in tetrahydrofuran (480 mL). During the addition the internal temperature should not exceed 20°C (Notes 13 and 14). After completion of the addition, the reaction mixture is heated at reflux for 1.5 hr using an oil bath, then cooled to room temperature. 

In order to remove the ethanol, the crystals are dissolved in toluene (3 mL per g of clathrate) at 70°C, and the solution is evaporated to dryness on a rotary evaporator at 45°C/100 mm. This procedure is repeated once more. A portion of the solid so obtained (68.5 g) is mixed with toluene (800 mL) at 80°C in a 2-L, two-necked, round-bottomed flask equipped with an overhead, mechanical stirrer, until the TADDOL [(R,R)-2,2-dimethyl-a,a,a, a -tetra(naphth-2-yl)-1,3-dioxolane-4, 5 -dimethanol] is... 

The procedure described here is a typical one tor the preparation of a,a,a ,a -tetraaryl 2,2-disubstituted 1,3-dioxolane-4,5-dimethanols (TADDOLs, 1), a class of diols of which ca. 50 representatives have been synthesized.7 They have become useful chiral auxiliaries for the preparation of enantiomerically enriched or pure compounds and for analytical purposes. The diols themselves have been employed... 

In 2(K)3, Rawal reported the use of TADDOLs (tetraaryl-1,3-dioxolan-4,5-dimethanol) as chiral H-bonding catalysts to facilitate highly enantioselective hetero-Diels-Alder reactions (393). Not surprisingly, this impressive protocol has soon found its way into the repertoire of organic chemists interested in natural product synthesis (394, 395). 

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