Approach to the stereoselective synthesis of (R)- and (S)-4-methoxydalbergione via asymmetric catalytic hydrogenation

✍ Scribed by Philippe Bissel; Rafaël Sablong; Jean-Pierre Lepoittevin

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 227 KB
• Volume: 6
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/0957-4166(95)00082-z

✦ Synopsis

Compound 7, a precursor in the synthesis of 4-methoxybalbergione, was prepared from compound 6 with an enantiomeric excess of 17 to 94% by asymmetric catalytic hydrogenation using rhodium or ruthenium chiral complexes. The best hydrogenation results were obtained using [Rh((S,S)-bdpp)(NBD)1 Cl04, and [Rh((R,R)-bdpp)(NBD)] Cl04, at a hydrogen pressure of 80 bar.

Dalbergiones belong to a small family of quinones found in tropical woods, 1,2 mainly in Dalbergia and Machaerium species, and are responsible for allergic contact dermatitis (ACD) reactions in patients coming into contact with these plants.3, 4 These optically active quinones have been determined to have an S or an R absolute configuration, except for 4-methoxydalbergione, which can be found in either form depending on its