Efficient general synthesis of 1,2- and 1,3-diols in high enantiomeric excess via the intramolecular asymmetric reduction of the corresponding ketoalkyl diisopinocampheylborinate intermediates

✍ Scribed by P.Veeraraghavan Ramachandran; Zhi-Hui Lu; Herbert C. Brown

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 270 KB
• Volume: 38
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(96)02447-1

✦ Synopsis

The first successful asymmetric reduction of unhindered aliphatic ketones with Bchlorodiisopinocampheylborane is reported. In contrast to the reduction in high ee of aralkyl ketones, such as acetophenone, with the reagent, the reduction of unhindered dialkyl ketones, such as 3-methyl-2-butanone, provides only poor ee. However, treatment of ct-and 13-hydroxyketones with one equiv of diisopinocampheylhorane or B-chiorodiisopinocampheylborane rapidly produces the corresponding ketoalkyl diisopinocampheylborinate intermediates, which then undergo facile intramolecular reduction. This reaction sequence, followed by oxidative workup, provides a general synthesis of 1,2and 1,3-diols in 84-_>99% enantiomeric excess.