Binaphthol, inclusion compounds

Some other resolutions by inclusion complexation with achiral host and by distillation technique are also described. In the last section, progress of the resolution of binaphthol, biphenols and related compounds is described. 

Some amide derivatives have been reported to form inclusion complex with a wide variety of organic compounds.9 Optically active amide derivatives are expected to include one enantiomer of a racemic guest selectively. According to this idea, some amide derivatives of tartaric acid (11-13) were designed as chiral hosts.10 As will be described in the following section, these amide hosts were found to be useful for resolution of binaphthol (BNO) (14) and related compounds (15,16). 

As the inclusion capacity of a host compound cannot be precisely predicted as yet, the work of the preparative chemist at the time being is reduced to systematic variation, design and further development of substance families, which are knoivn to constitute clathrate formers. The numerous complex forming agents derived from binaphthol have been mentioned already in section 2A. 

If host and guest molecules mutually recognize their chiralities at inclusion formation, the process could be used for optical resolution. In other words, when the host compound is optically active, one enantiomer of the guest compound should be included selectively. In turn, if an optical active guest molecule forms a crystal inclusion with one enantiomer of the host compound selectively, the host compound yields resolved. This section deals with the resolution via inclusion formation using host compounds such as alkaloids, 2-propyn-l-ols, 2,4-hexadiyne-l,6-diols, 2,2 -dihydroxy-l,r-binaphthol (7), and 2,2 -dihydroxy-9,9 -spirobifluorene (10a). 

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