Synthesis of the Dibenzofuran-Based Diphosphine Ligand BIFAP and Its Water-Soluble Derivative BIFAPS and Their Use in Ruthenium-Catalyzed Asymmetric Hydrogenation.[≠]

✍ Scribed by Arjan E. Sollewijn Gelpke; Huub Kooijman; Anthony L. Spek; Henk Hiemstra

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 236 KB
• Volume: 5
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/(sici)1521-3765(19990903)5:9<2472::aid-chem2472>3.0.co;2-v

✦ Synopsis

The syntheses of both enantiomers of the novel diphosphine ligand 2,2'-bis(diphenylphosphanyl)-1,1'-bidibenzofuranyl (BIFAP, 1) and the watersoluble analogue (À)-2,2'-bis(diphenylphosphanyl)-1,1'-bidibenzofuranyl-8,8'disulfonic acid dipotassium salt (BI-FAPS, 2) are reported. Advantage is taken of the very high regioselectivity in ring functionalisation of the 1,1'-bidi-benzofuranyl backbone. These ligands are used in the ruthenium-catalysed hydrogenation of methyl acetoacetate and (Z)-acetamidocinnamic acid in methanol and water. In methanol both BIFAP and BIFAPS give the products in very high enantiomeric excess. With BIFAPS in water a slight drop in the ee of the products is observed. When BIFAPS is used with either water or methanol as the solvent the addition of a small amount of acid turns out to be essential for a fast reaction and high asymmetric induction.