Improved RuO4-catalysed oxidative cyclisation of geraniol-type 1,5-dienes to cis-2,5-bis(hydroxymethyl)tetrahydrofuranyldiols

✍ Scribed by Vincenzo Piccialli; Nicola Cavallo

• Publisher: Elsevier Science
• Year: 2001
• Tongue: French
• Weight: 158 KB
• Volume: 42
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)00790-0

✦ Synopsis

The oxidation of some representative 1,5-dienes based on the geraniol and nerol carbon skeletons, namely geranyl acetate (1), geranic acid methyl ester (5), trans,trans-2,6-dimethyl-2,6-octadiene-1,8-diol diacetate (9), neryl acetate (13) and neroic acid methyl ester ( 16), has been performed using catalytic amounts of RuO 4 (from RuO 2 •2H 2 O, 4%) in the presence of NaIO 4 (4 equiv.) as co-oxidant in the solvent mixture EtOAc/CH 3 CN/H 2 O (3:3:1) at 0°C for 4 min. These conditions assure a degree of stereoselectivity for the geraniol-type dienes higher than that obtained under the Sharpless conditions [RuCl 3 •(H 2 O) n (2.2%), NaIO 4 (3.1 equiv.), CCl 4 /CH 3 CN/H 2 O (2:2:3), 0°C], furnishing the cis-and trans-THF diol products in 62-70 and 6-9% yields, respectively. In addition, the amount of the cis-THF, C-2 overoxidised, product is strongly reduced (2-7%). A comparison with the related MnO 4 --induced process, tested on the same substrates, was made.