Tetramethyltartaric acid

While ot,3-unsaturated aldehydes react exclusively with triotganoaluminums in the 1,2-mode, the identical reaction of the corresponding chiral a,3-unsaturated acetals (5), obtained from (RJi)-(+)-N V V V -tetramethyltartaric acid amides, is solvent dependent." For example, in 1,2-dichloroethane, preferential y-addition (Sn2 ) occurs (5 giving 7 Scheme 2), while in dichloromethane, preferential a-addition occurs (5 giving 8 Scheme 2). Subsequent hydrolysis of (7) affords the -substituted aldehydes in high enantiomeric purity (Scheme 2) thus the acetals (5) serve as effective surrogates for —CH=CH—CHO (+CH2CH2CHO). 

A double 0-methylation of (f ,/ )-(+)-N,N,N NI-tetramethyltartaric acid diamide (113.1) was accomplished on a mole scale without racemisation [Scheme 4 113]204 using phase transfer catalysis. The reaction was conducted in a two-phase mixture consisting of 50% sodium hydroxide and dichloromethane,... 

The chiral acetals of a,p-enals derived from (H,R)-( -I-)-N,N,N, N -tetramethyltartaric acid diamide (9, 47-48) undergo either 1,4- or I. . .-addition of R,AI with high asymmetric induction. The course of reaction can be controlled by the choice of solvent. 1,4-Addition is favored in 1,2-dichloroethane (or toluene) 1,2 addition is the main or only reaction in chloroform. The adducts can be converted into optically active p-alkyl aldehydes or allylic alcohols (Chart I). ... 

Preparative Methods the reagent is easily prepared from commercially available butylboronic acid (or its more stable diethanolamine complex) and RJi)-(+)-N,NJ4 J4 -tetramethyltartaric acid diamide. The other enantiomer is also... 

A much higher and more efficient chiral version (>90%) of the cyclopropanation of allylic alcohols is obtained by using the amphoteric bifunctional ligand (R,R)-93 prepared from commercially available (+)-(/ ,7 )-At,TV,A, A -tetramethyltartaric acid diamide and butyl-boronic acid. The dioxyborolane chiral ligand proved to be extremely effective with several types of substituted allylic alcohols 92. The chiral ligand 93 can easily be removed and recovered (> 80%) by a simple aqueous extraction of the organic layer after the reaction. 

To a solution of (-l-)-A,A,iV, A -tetramethyltartaric acid diamide (30.6 g, 0.15 mol) in anhyd toluene (100 mL) was added butylboronic acid (18.3 g, 0.18 mol). The mixture was heated under reflux in a Dean-Stark apparatus for 15 h to remove the water produced in the reaction. The mixture was cooled to rt and concentrated under reduced pressure. The residue was dissolved in a minimum of CH2CI2, filtered to remove the excess of butylboronic acid and concentrated under reduced pressure yield 37.8 g (93%). 

Recovery of (R,R)-(+)-N,N,N, N -tetramethyltartaric acid diamide. The aqueous layer from the above extraction is concentrated under reduced pressure, and the crude product is recrystallized by an initial dissolution in hot dichloromethane (5 mL) followed by the addition of ethyl acetate (10 mL) to afford between 600 mg to 750 mg (33-41% yield) of the (R,R)-(+)-N,N,N ,N -tetramethyltartaric acid diamide (Notes 36 and 37). 

More recently, dioxaborolane derived from (RR)- +)-N,N,N, W -tetramethyltartaric acid diamide has been used as an efficient chiral controller in Simmons Smith cyclopropanation reaction of allylic alcohols to produce substituted cyclopropyl methanols in high... 

High enantioselectivities are obtained using N,N,N, N -tetramethyltartaric acid diamide-derived boronate ester 32 in combination with bis(iodomethyl)zinc for asymmetric cyclopropanation of allylic alcohols. Various chiral, non-racemic cyclopropyl-methanols can be obtained in enantiomeric excesses of 91-94%. This methodology has been extended with success to the cyclopropanation of unconjugated and conjugated polyenes and homoallylic alcohols (Equation 47) [45]. 

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