H8-BINOL

Guo and co-workers have disclosed the first highly enatioselective alkylation reaction of enamides (220) with indolyl alcohols (221) catalyzed by phosphoric acid (223) derived from H8-BINOL affording (ff-aryl 3-(3 indolyl)propanones (222) in high yields (up to 96%) and excellent enan-tioselectivity (up to 96% ee) (Scheme 61). 

N-Boc-aldimines. Various chiral Bronsted acids were tested and the best results in terms of yields and ee values were observed with the commercially available (5)-H8-BINOL 52 (Scheme 24.18). 

In 2009, Gong s group reported the dynamic kinetic transfer hydrogenation reaction of 2-methyl-2,4-diaryl-2,3-dihydrobenzo[ )][l,4]diazepines, using chiral phosphoric acids as organocatalysts and Hantzsch ester as the hydride source. ° A 3,3 -H8-BINOL-derived phosphoric acid was identified as the optimal chiral catalyst for this process, affording the corresponding 1,3-diamine derivatives with moderate diastereoselectivities of up to 78% de, and enan-tioselectivities of up to 94% ee, as shown in Scheme 2.107. 

Spirocyclic phosphoric acid catalyst STRIP (6) turned out to be crucial in the development of the kinetic resolution of homoaldols. The SPINOL backbone outperformed a variety of other previously described phosphoric acids based on BINOL (3 and 2), H8-B1NOL (9), VAPOL (1), and TADDOL (10) backbones (Table 2). 

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