Chiral synthesis VIA organoboranes. 26. An efficient synthesis of isoprenyl derivatives of borane - valuable reagents for the isoprenylboration of aldehydes. A convenient route to both enantiomers of ipsenol and ipsdienol in high optical purity
作者:Herbert C. Brown、Ramnarayan S. Randad
DOI:10.1016/s0040-4020(01)85575-7
日期:1990.1
namely metallation of isoprene with potassium 2,2,5,5-tetramethylpiperidide followed by sequential treatment with B-methoxydialkylborane and boron trifluoride-etherate. These reagents are used for the convenient isoprenylation of aldehydes. Reaction of isovaleraldehyde and β, β-dimethylacrolein with B2'isoprenyldiisopinocampheylborane provides both ipsenol and ipsdienol, respectively in 65% yields and 96%
B-异戊二烯基二烷基硼烷的制备是通过采用Schlosser程序的Brandsma改性完成的,即用2,2,5,5-四甲基哌啶钾对异戊二烯进行金属化,然后依次用B-甲氧基二烷基硼烷和三氟化硼-醚化物处理。这些试剂用于方便的醛异戊二烯化。异戊醛和β,β-二甲基丙烯醛与B 2'异戊二烯基二异辛基环戊基硼烷的反应分别提供了ipsenol和ipsdienol,产率为65%,ee为96%。