Ra-Ni (W-2)

• 英文名称: Ra-Ni (W-2)

反应信息

• 作为试剂：
  描述：

  2,6,6-三甲基-2-环己烯-1,4-二酮 在 Ra-Ni (W-2) 咪唑 、 sodium tetrahydroborate 、 重铬酸吡啶 、 cerium(III) chloride 、 氢气 作用下， 以 甲醇 、 乙醇 、 N,N-二甲基甲酰胺 为溶剂， 反应 30.0h， 生成 (4R,6RS)-4-tert-butyldimethylsilyloxy-2,6,6-trimethylcyclohexanone
  参考文献：
  名称：

  Lipase-catalyzed asymmetric synthesis of (R)- and (S)-4-tert-butyldimethylsilyloxy-2,6,6-trimethyl-2-cyclohexenone and their dihydro derivatives

  摘要：

  Racemic 4-hydroxy-2,6,6-trimethyl-2-cyclohexenon trans- and cis-2,6,6-trimethyl-2-cyclohexene-1,4-diols were prepared by reduction of 4-oxoisophorone with sodium borohydride-cerium chloride. Lipase (PS-30)-catalyzed kinetic resolution of (+/-)-cis-2,6,6-trimethyl-2-cyclohexene-1,4-diol with vinyl acetate led to (1R, 4S)-4-acetoxy-2,6, 6-trimethyl-2-cyclohexen-1-ol (81 %ee);and (1S, 4K)-1-acetoxy-2,6,6-trimethyl-2-cyclohexene-4-ol (92 %ee). Hydrolysis of the former monoacetate and recrytallization of the resulting material afforded enantiomerically pure (1R, 4S)-2,6,6-trimethyl-2-cyclohexene-1,4-diol. On the other hand, recrystallization of (1S, 4R) monoacetate itself provided an optically pure sample, which was then hydrolyzed to give (1S, 417)-2,6,6-trimethylcyclohexene-1,4-diol. Transformation of both diols into (S)- and (R)-4-tert-butyldimethylsilyloxy-2,6,6-trimethyl-2-cyclohexenone was conducted in two steps including silylation and oxidation. Catalytic hydrogenation of these (S)- and(R)-silyloxy enones dyer Raney nickel afforded the corresponding dihydro derivatives.

  DOI：

  10.1016/0957-4166(95)00159-m