Binaphthol host resolution

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). 

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). 

An established area of application of macrocyclic polyethers is the stereoselective complexation of chiral guest primary alkylammonium salts by optically active host macrocycles. Full details of the resolution, optical stability, and inclusion into chiral hosts of the binaphthol (84), and also of the chiral recognition properties of crowns [e.g. (85)] based on simple carbohydrate precursors, have been reported this year. An extension of the latter work" utilizes derivatives of the more complex carbohydrates D-glucose and D-galactose. The macrobicyclic polyethers (86) derived from D-glycerol or pentaerythritol have been suggested as potential chiral (at the bridgeheads) cryptands. 

---