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Shinsaku Fujita 《Tetrahedron》2004,60(50):11629-11638
The concepts of holantimer and stereoisogram are applied to comprehensive discussions on the term ‘pseudoasymmetry’, where the concept of RS-stereogenicity is used as a more definite concept than usual stereogenicity. Thereby, three relationships contained in each stereoisogram can be definitely specified: an enantiomeric relationship is related to chiral/achiral, an RS-diastereomeric relationship is related to RS-stereogenic/RS-astereogenic, and a holantimeric relationship is related to scleral/ascleral, which is coined to keep the terminology in a balanced fashion. Such stereoisograms are classified into five types (Types I-V) by virtue of the three relationships. Among them, Type I, III, and V are selected as a set of RS-stereogenic units: chiral/ascleral RS-stereogenic unit (or Type I unit), chiral/scleral RS-stereogenic unit (or Type III unit), and achiral/scleral RS-stereogenic unit (or Type V unit). Thereby, the term ‘pseudoasymmetric stereogenic units’ should be replaced by the term ‘achiral/scleral RS-stereogenic units’ (or ‘Type V units’). 相似文献
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Tanno A. Schmidt Stephan Schumann Andreas Ostertag Prof. Dr. Christof Sparr 《Angewandte Chemie (International ed. in English)》2023,62(21):e202302084
Catalyst control over higher-order stereogenicity addresses significantly extended stereochemical space, but selective methods to govern threefold stereogenic units remained elusive. Herein, we report the stereoselective synthesis of threefold stereogenic triptycyl sulfones with atropisomerism arising from a C(sp3)−S bond. An oxidation of a stereodynamic thioether controlled by a chiral phosphoric acid catalyst allowed selective access to enantioenriched triptycyl sulfoxides. The ensuing enantiospecific and diastereoselective catalytic oxidation to a threefold stereogenic sulfone provided overall control over the stereogenic C−S axis. All three stereoisomers were addressable with enantio- and diastereodivergence and a stereoselectivity of up to (−sc): (+sc) : (ap)=94 : 6 :<1. 相似文献
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