Kawabata, Takeo

Takeo Kawabata of the Institute for Chemical Research associated with Kyoto University reports (J. Am. Chem. Soc. 125 13012,2003) that unnatural amino acids can also be used to assemble four-, five-, six-, and seven-membered cyclic amines having quaternary stereogenic centers. Given the conventional wisdom that ester enolates are sp -hybridized, this memory effect is remarkable. 

Molecules can often surprise us in their ability to retain stereochemical information despite what appear to be stereorandomizing processes. In Chapter Three by Takeo Kawabata and Kaoru Fuji a fascinating manifestation of this phenomenon is illustrated, explained and exemplified in the chemistry of eno-lates derived from sterically congested ketones and a-amino acid derivatives. Although these enolates are certainly planar species, the stereochemical consequences of the ancillary substituents have, until now been unappreciated. This... 

Takeo Kawabata of Kyoto University found (J. Am. Chem. Soc. 2008, 130, 4153) that intramolecular alkylation to form four, five and six-membered rings from amino esters such as 21 proceeded with remarkable enantioretention. 

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