TADDOLs, which contain two adjacent diarylhydroxymethyl groups in a trans relationship on a 1,3-dioxolane ring, can be prepared from acetals or ketals of tartrate esters by reaction of the latter with aromatic Grignard reagents. They are extraordinarily versatile chiral auxiliaries. Here, a historical review of the subject is followed by discussion of the preparation of TADDOLs and analogous systems, including TADDOLs with N-, P-, O-, and S-heteroatom ligands appropriate for metals. Crystal structure analysis reveals that the heteroatoms on the diarylmethyl groups are almost always in close proximity to each other, joined together by H-bonds, and predisposed to form chelate complexes in which the metallic centers reside in propeller-like chiral environments. Applications of TADDOL derivatives in enantioselective synthesis extend from utilization as stoichiometric chiral reagents or in Lewis acid mediated reactions, to roles in catalytic hydrogenation and stereoregular metathesis polymerization. Derivatives and complexes based on the following metals have so far been investigated: Li, B, Mg, Al, Si, Cu, Zn, Ce, Ti, Zr, Mo, Rh, Ir, Pd, Pt. The number of stereoselective reactions already accomplished with TADDOLs is correspondingly large. It is also easy to prepare TADDOL derivatives that are readily polymerizable and graftable, and to transform them into immobilized solid-phase catalysts. The result is catalysts, simply or dendritically immobilized in polystyrene or on silica gel and characterized by unexpected stability even after multiple use in titanium TADDOLate mediated reactions. TADDOLs show further unusual characteristics that make them useful for applications in material science and supramolecular chemistry: they are the most effective doping agents known for phase transformations of achiral (nematic) into chiral (cholesteric) liquid crystals. The TADDOL OH group that is not involved in intramolecular H-bonding shows a strong tendency to associate intermolecularly with H-bond acceptors. In the process of crystallization this leads, enantioselectively, to the formation of inclusion compounds that lend themselves to the separation of racemic mixtures not otherwise suited to the classical method of crystallization through diastereomeric salts. The high melting points of TADDOLs even make possible the resolution of racemates by distillation! Host-guest compounds formed between TADDOLs and achiral partners can serve as platforms for enantioselective photoreactions. It seems safe to predict that many more applications will be discovered for the TADDOLs and their derivatives. Supporting information for this article is available on the WWW under http://www.angewandte.com or from the author.

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TADDOLs, Their Derivatives, and TADDOL Analogues: Versatile Chiral Auxiliaries

Recent developments in lanthanide mediated organic synthesis

TADDOLe, ihre Derivate und Analoga – vielseitige chirale Hilfsstoffe

The present invention provides a compound of formula (I) and the use thereof for the therapeutic treatment, prevention or amelioration of a disease or disorder characterized by elevated s-amyloid deposits or s-amyloid levels in a patient

Amino-5,5-diphenylimidazolone derivatives for the inhibition of beta-secretase

Applications of CeCl3 as an Environmental Friendly Promoter in Organic Chemistry

An improved procedure for the synthesis of 4,4-disubstituted-3-oxo-1,2,5-thiadiazolidine 1,1 -dioxides

Cerium (III) chloride mediated nitrile aldol reactions: Enhanced diastereoselectivities using a chiral organocerium complex

An elimination reaction of N-carbomethoxy-N,N-dimethylhydrazonium salts to alkyl nitriles

An improved synthesis for the preparation of 3-oxo-1,2,5-thiadiazolidine 1,1-dioxides has been developed. This facile two-step procedure fromα-amino acid esters and chlorosulfonyl isocyanate results in excellent yields of products.

An Improved Procedure for the Synthesis of 4,4-Disubstituted-3-oxo-1,2,5-thiadiazolidine 1,1-Dioxides.

We studied the nucleophilic addition of organocerium reagents to α-alkoxy hydrazones. The results depend upon the organocerium reagents, the nature of protection for the hydroxy group, and the solvents used. Contrary to Grignard reagents, organocerium reagents derived from Grignard reagents effectively add to α-alkoxy hydrazones. In addition, a new type of elimination reaction of α-alkoxy hydrazones to the corresponding nitriles by methyl chloroformate was found. This methodology is an efficient and potentially practical synthetic route to β-hydroxy amines. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:65–72, 2000

Zejun Xiao

Papers

An improved procedure for the synthesis of 4,4-disubstituted-3-oxo-1,2,5-thiadiazolidine 1,1 -dioxides

Cerium (III) chloride mediated nitrile aldol reactions: Enhanced diastereoselectivities using a chiral organocerium complex

An elimination reaction of N-carbomethoxy-N,N-dimethylhydrazonium salts to alkyl nitriles

An Improved Procedure for the Synthesis of 4,4-Disubstituted-3-oxo-1,2,5-thiadiazolidine 1,1-Dioxides.

Nucleophilic addition of organocerium reagents to?-alkoxy hydrazones: A new type of elimination reaction to?-hydroxynitriles