Diamine salts, binaphthyl-based

Maruoka, et al. reported unprecedented high exo-selectivity in the asymmetric Diels-Alder reaction of a, 3-unsaturated aldehydes by a protonic acid-(i )-binaphthyl-based diamine salt catalyst 48, Scheme 3.15 [27], On the other hand, the Diels-Alder reaction of cyclopentadiene and cinnamaldehyde via enantioselective catalysis over mesocellular foams was reported by Ying and his co-workers [28]. 

The hydroxy-binaphthyl functionalised saturated imidazolium salt is readily available from 1-amino-I -hydroxy-binaphthyl in a reaction with a ( oc-protected mesitylamine aldehyde [86] (see Figure 4.24). The resulting Schiff base is reduced to the diamine by Na(OAc)3BH. Subsequent deprotection and ring closure reaction with triethyl orthoformate yields the corresponding hydroxy-binaphthyl functionalised saturated imidazolium salt. Reaction with silver(I) carbonate and subsequent carbene transfer to the ruthenium(II) precursor yields the asymmetric olefin metathesis precatalyst. 

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