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Industrially Viable Syntheses of Highly Enantiomerically Enriched 1-Aryl Alcohols via Asymmetric Hydrogenation

2002; American Chemical Society; Volume: 7; Issue: 1 Linguagem: Inglês

10.1021/op025585r

1520-586X

David A. Chaplin, Paul Harrison, Julian P. Henschke, Ian C. Lennon, Graham Meek, Paul H. Moran, Christopher J. Pilkington, James A. Ramsden, Simon Watkins, Antonio Zanotti‐Gerosa,

Catalysis for Biomass Conversion

The practicalities of the asymmetric hydrogenation of acetophenone derivatives are addressed. The catalysts used, derived from the precatalysts [(xylylPhanePhos)RuCl2(DPEN)] (S)-(R,R)-1 and (R)-(S,S)-1, were shown to possess very high reactivity. 4'-Fluoroacetophenone was hydrogenated at a molar substrate-to-catalyst ratio (S/C) of 100,000 with complete conversion effected in as little as 80 min (average turnover ∼1200 min-1, peak turnover ∼2500 min-1). The catalysts are tolerant of a range of commercial grade substrates, in most cases a S/C of 5000−10000 was achieved without the need to purify the ketone. Using precatalyst 1 enantioselectivities of 95 → 99% ee were achieved. The high selectivity and catalyst activity, plus the simplicity of the process, offers significant advantages over other enantioselective ketone reductions.