Design and Synthesis of Spirochroman‐2‐on‐4,1'‐indan‐7'‐ol and Its Application for Synthesizing Chiral Monophosphinite Ligands†

Abstract

Comprehensive SummaryThe design and synthesis of spirochroman‐2‐on‐4,1'‐indan‐7'‐ol (SCIOL) and its application for synthesizing chiral monophosphinite ligands are reported. The synthesis features a tandem double Friedel‐Crafts reaction/lactonization to construct the spiro framework and the desired racemic SCIOL was obtained via 6 steps with a total yield of 44.5%. Using an inclusion resolution with N‐benzylcinchonidinium chloride, the optical SCIOL could be obtained in good yields on a gram scale. The preliminary studies indicated that the corresponding chiral spiro monophosphinite ligands exhibit high catalytic activity and enantioselectivity (up to 94% ee) in the rhodium‐catalyzed asymmetric hydrogenation of N‐acetyl dehydroamino esters. These outcomes highlight the significant potential of SCIOL as a useful framework for the development of chiral spiro ligands.