Chiral benzo-14-crown-4 derivatives

A chiral benzo-14-crown-4 derivative (RR)-T1 has been prepared (121) from (2J ,3J )-2,3-butanediol by applying to the chiral diol a chain extension procedure that involves (i) addition of aciylonitrile to both hydroxyl groups, (ii)... 

The incoiporation of two asymmetric precursors into chiral crown ethers with C2 symmetiy must be carried out with total constitutional and stereochemical control during the reaction sequence. This has been accomplished elegantly during the synthesis of the three chiral benzo-15-crown-5 derivatives (SS)-79, and (5S)- 0 from (S)-lactic acid (122, 123). 

Chiral 18-crown-6 derivatives incorporating both one and two L-glyceralde-hyde dithioethylacetal residues have also been reported (128) recently. Also, a benzo-18-crown-6 ring has been appended (129) to the C-5 and C-6 positions of 1,2-0-isopropylidene-3-(9-methyl-a-D-glucofuranose. 

A number of benzo-15-crown-5 derivatives are known where chirality is associated with side chains or fused ring systems. For example, base-promoted reactions of l,ll-dichloro-3,6,9,-trioxaundecane with apomorphine and adrenaline have afforded the benzo-lS-crown-S derivatives 164 and 165, respectively... 

Bis(2-hydroxypropyl)(phenyl)phosphine oxide 121 is a suitable chiral precursor for the synthesis of l-phospha-ll,12-benzo-21-crown-7 123 and l-phospha-10-aza-18-crown-6 122 derivatives, the first examples of optically pure, crown-ether-like, phosphorus-containing macrocycles (Scheme 12.47). The com-plexation of Na" by the crown ether moiety of the macrocyclic ring has been observed [107]. 

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