Hydroboration of mono-substituted allenes: A general synthetic route to the higher crotylboranes and anti-3-alkyl/aryl-4-hydroxy-1-alkenes

✍ Scribed by Gowriswari Narla; Herbert C. Brown

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 221 KB
• Volume: 38
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(96)02255-1

✦ Synopsis

Hydroboration of mono-substituted allenes with Chx2BH at 0 *(2 leads to the corresponding (E)substituted allylboranes, known as higher crotylboranes, exclusively. These higher cmtylboranes react with aldehydes, and on oxidation, provide the corresponding anti.3.alkyl/aryl-4.hydroxy-l-alkenes in high diastereomeric excess. By changing the hydroborating reagent to Ipc2BH, synthesis of the corresponding optically active anti-3-alkyVaryl-4.hydroxy-1-alkenes is achieved in excellent diastereo-and good enantioselectivities.