Development of a Highly Stereoselective Remote Asymmetric Induction Method by Means of the Binaphthalene-Template Conformation Control

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We have developed diastereoselective asymmetric reactions using the 2,2'-positions of 1, l'-binaphthyl compounds as a chiral field. Synthesis of novel binaphthyls and thiacalixarenes and exploration of the functions of the latter compounds are the other targets of this research. The summary of the results is itemized as follows : 1. Treatment of gamma-keto esters of l , 1'-binaphthyl-2-ol bearing an appropriate oligoether tether at the 2'-position with DIBAL-H in the presence of magnesium bromide gave, after LAH reduction of the resulting diastereomeric hydroxy esters, I , 4-diols with high enantiomeric excesses. On the other hand, Grignard reaction of the relevant gamma-keto esters gave gamma-lactones having a chiral quaternary carbon center with up to 99% ee. 2. The remote asymmetric inductive Grignard reaction was found to be applicable to delta- and epsilon-keto esters and was advantageously utilized for the synthesis of a marine antibiotic, malyngolide. 3. The corresponding Grignard reaction of zeta- to theta-keto esters was realized by using BINOL as the chiral auxiliary. Thus, the Grignard reaction of the mono omega-keto esters of BINOL in the presence of magnesium bromide proceeded with more than 80% de. 4. Several binaphthyl compounds were effectively prepared in an atropisomeric or racemic form via the nucleophilic aromatic substitution on 1-alkoxynaphthalenes bearing an ester, sulfonyl, or nitro group at the 2-position as the activating group by 1-naphthyl Grignard reagents. 5. A novel calixarene, p-tert-butylthiacalix[4]arene, which is expected to be a potential substitute for BINOL framework, was effectively prepared from p-tert-butylphenol and powdered sulfur. The derivatives were found to function as a host molecule to bind specific metal ions and toxic halogenated organic compounds and as a chirality-recognizing element for a stationary phase for gas chromatography.