New convenient approach to the preparation of (Z)-allylic boronates via catalytic 1,4-hydroboration of 1,3-dienes with catecholborane

✍ Scribed by Makoto Satoh; Yoshihiro Nomoto; Norio Miyaura; Akira Suzuki

• Book ID: 104233099
• Publisher: Elsevier Science
• Year: 1989
• Tongue: French
• Weight: 264 KB
• Volume: 30
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)80656-0

✦ Synopsis

cyclohexadiene with catecholborane (1,3,2+enzodioxaborole) in the presence of Pd(PPh& or Rh4(CO)I, catalysts proceeds smoothly to provide 2-[(Z)-2-alkyl-2-butenyl]-1,3,2-benzodioxaboroles in very high regio-and stereoselectivity. Much attention is being denoted to the reactions of allylic boron reagents with carbonyl compounds for the synthesis of homoallylic alchols in high diastereoselectivityl or enantioselectivity.*,z (E)-and (Z)-Crotylboronates1s2 were prepared by the method originally reported by SchJosse? from (E)-and (Z)crotylpotassiums and haIoboron compounds, The procedure, in spite of the multi-step process, has an advantage that the both (E)-and (Z)-crotylborates are obtained over 95% of isomeric purity. An alternative route4 to further subsitimted allylic boronates from halomethylborates and (E)-or (Z)-alkenyliithiums was

aho reported. On the other hand, it is known that selective monohydroboration of some dienes, such as 1,3-cyclohexadiene5 and 3-methyl-1,2-butadiene6, affords allylic boranes. Although the hydroboration approach is simple and convenient, the method is not applicable to usual 1,3dienes because the hydroboration mainly ocxus