Bicyclo[2.2.2]octane-derived chiral ligands-synthesis and application of BODOLs in the asymmetric reduction of acetophenone with catecholborane

Summary, in English

An improved synthetic route to the bicyclo[2.2.2]octane-2,6-diol ligands (2,6-BODOLS) allowed an increased structural variation of the ligand side-arm. The addition of aromatic or vinylic Grignard reagents to hydroxyketone 1 was highly selective and ligands 3f-3I were isolated in 84-97% yield. The addition of alkyl Grignard reagents containing beta-hydrogens resulted in lower yields (13-71%) due to competing ketone reduction. A number of 2,5-BODOLs were synthesized using a similar methodology. The ligands, together with Ti(OiPr)(4), were tested in the asymmetric reduction of acetophenone with catecholborane (up to 98% ee). 1-Naphthyl-BODOL 3i was employed as an allylboration reagent to benzaldehyde together with Sc(OTf)(3), resulting in (1S)-1-phenyl-3-buten-1-ol in 80% ee. (C) 2008 Elsevier Ltd. All rights reserved.

• Author: Annika Friberg; Ian Sarvary; Ola Wendt; Torbjörn Frejd
• Department/s: Centre for Analysis and Synthesis
• Publishing year: 2008
• Language: English
• Pages: 1765-1777
• Publication/Series: Tetrahedron: Asymmetry
• Volume: 19
• Issue: 15
• Links: http://dx.doi.org/10.1016/j.tetasy.2008.07.006
• Document type: Journal article
• Publisher: Elsevier
• Topic: Organic Chemistry
• Status: Published
• ISBN/ISSN/Other: ISSN: 0957-4166