BINOL monoethers

Epoxide opening. Optically active trans-1,2-diol monoethers are readily obtained by the catalyzed reaction of epoxides with alcohols in the presence of the BINOL complexes and molecular sieves 4A. Similarly, p-hydroxy sulfides are formed. ... 

The Ga-Li-BINOL complex 4 was discovered by Shibasaki to catalyze the ring opening of epoxides with 4-methoxyphenol. Elevated temperatures and high catalyst loadings render this catalyst system less practical than the ferf-butyl thiol counterpart,but the hydroxy aryl monoethers produced in this reaction do offer access to valuable monoprotected 1,2-frans-diols (Scheme 8) [21]. 

Aryloxy alcohols. These glycol monoethers are formed by epoxide opening. From meso-epoxides, chiral products are obtained in the presence of the linked BINOL complex. Reaction with simple BINOLs is complicated by erosion of enantioselectivity due to phenolate exchange (i.e., BINOL and phenolate nucleophile). 

Fig. 8.143 Example of In and Ga monoether BINOL complexes catalyzed epoxide ring opening with TMSCN.

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