Development of Chiral Spiro Phosphoramidites for Rhodium‐Catalyzed Enantioselective Reactions.

A series of 1,1′‐spirobiindane‐7,7′‐diol (SPINOL) analogues bearing a 2,2′‐dimethyl‐, cyclopentyl‐, or cyclohexyl‐fused ring were synthesized, and their distinct structural features were elucidated by X‐ray crystallography. On the basis of these scaffolds, chiral monophosphoramidite ligands 6 a–m were synthesized, which demonstrated excellent enantioselectivity in RhI‐catalyzed asymmetric hydrogenation of a dehydro amino acid methyl ester. Ligands 6 a–m were also successfully applied in the RhI‐catalyzed enantioselective [4+2] cycloaddition of α,β‐unsaturated imines with isocyanates, which afforded the corresponding pyrimidinones in good yields (60–92 %) with high enantioselectivities (75–92 % ee). [ABSTRACT FROM AUTHOR]