TADDOL-derived phosphites and phosphoramidites for efficient rhodium-catalyzed asymmetric hydroboration
Shin A Moteki1, Di Wu, Kusum L Chandra
1Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, 68588, USA.
Abstract:
[reaction: see text] Two simple TADDOL-derived monodentate ligands, the (1R,2S)-2-phenylcyclohexanol-derived phosphite and the N,N-(phenylbenzyl)phosphoramidite, give comparably high levels of enantioselectivity (90-96% ee) in the rhodium-catalyzed hydroborations of substituted styrenes bearing either electron-donating or electron-withdrawing substituents. Rhodium(I) chloride and tetrafluoroborate catalyst precursors give comparable results. Pinacolborane is superior to catecholborane in these reactions.
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