Organic synthesis using haloboration reaction. Part 9. A direct and selective synthesis of (Z,Z)-1-bromo-1,3-dienes and (E,Z)-1,3-dienes by the hydroboration-bromoboration sequence of two alkynes

✍ Scribed by Satoshi Hyuga; Satoru Takinami; Shoji Hara; Akira Suzuki

• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 227 KB
• Volume: 27
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)84153-2

✦ Synopsis

1-Alkenyldibromoboranes readily obtainable by the hydroboration of first alkyneswith dibromoborane-dimethyl sulfide followed by treatment with tribromoborane, react without any difficulty with second 1-alkynes as bromoborating agents to give (l-alkenyl)(Z-bromo-l-alkeny)bromoboranes (5). The reaction of $-with iodine in the presence of potassium acetate provides (Z,Z)-1-bromo-1,3-dienes (g), specifically, which are readily converted into the corresponding (E,Z)-1,3-dienes (7) by treatment with t-butyllithium and methanol.