• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Role of the NH2 functionality and solvent in terdentate CNN alkoxide ruthenium complexes for the fast transfer hydrogenation of ketones in 2-propanol
【24h】

Role of the NH2 functionality and solvent in terdentate CNN alkoxide ruthenium complexes for the fast transfer hydrogenation of ketones in 2-propanol

机译：NH2官能度和溶剂在CNN醇盐钌络合物中对2-丙醇中酮的快速转移加氢的作用

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The reaction of [RuCl-(CNN)(dppb)) (1; HCNN = 6-(4-methylphenyl)-2-pyridylmethylamine) with NaOiPr in 2-propanol/C6D6 affords the alcohol adduct alkoxide [Ru(OiPr)-(CNN)(dppb)]center dot niPrOH (5), containing the Ru-NH2 linkage. The alkoxide (Ru(OiPr)(CNN)(dppb)] (4) is formed by treatment of the hydride [Ru(H)(CNN)(dppb)] (2) with acetone in C6D6. Complex 5 in 2-propanol/C6D6 equilibrates quickly with hydride 2 and acetone with an exchange rate of (5.4 +/- 0.2) s(-1) at 25 degrees C, higher than that found between 4 and 2 ((2.9 +/- 0.4) s(-1)). This fast process, involving a beta-hydrogen elimination versus ketone insertion into the Ru-H bond, occurs within a hydrogen-bonding network favored by the Ru-NH2 motif. The cationic alcohol complex [Ru(CNN)(dppb)(iPrOH)](BAr4f) (6; Ar-f = 3,5-C6H3-(CF3)(2)), obtained from 1, Na[BAr4f], and 2-propanol, reacts with NaOiPr to afford 5. Complex 5 reacts with either 4,4'-difluorobenzophenone through hydride 2 or with 4,4'-difluorobenzhydrol through protonation, affording the alkoxide [Ru{OCH(4-C6H4F)(2)}(CNN)(dppb)] (7) in 90 and 85 % yield of the isolated product. The chiral CNN-ruthenium compound [RuCl(CNN)-{(S,S)-Skewphos}] (8), obtained by the reaction of [RuCl2(PPh3)(3)] with (S,S)-Skewphos and orthometalation of HCNN in the presence of NEt3, is a highly active catalyst for the enantioselective transfer hydrogenation of methylaryl ketones (turnover frequencies (TOFs) of up to 1.4 x 10(6) h(-1) at reflux were obtained) with up to 89 % ee. Also the ketone CF3CO(4-C6H4F), containing the strong electron-withdrawing CF3 group, is reduced to the R alcohol with 64 % ee and a TOF of 1.5 x 10(4) h(-1). The chiral alkoxide [Ru(OiPr)(CNN)-(S,S)-Skewphos)]center dot niPrOH (9), obtained from 8 and NaOiPr in the presence of 2-propanol, reacts with CF3CO-(4-C6H4F) to afford a mixture of the diastereomer alkoxides [Ru{OCH-(CF3)(4-C6H4F)}(CNN){(S,S)-Skewphos}] (10/11; 74 % yield) with 67 % de. This value is very close to the enantiomeric excess of the alcohol (R)-CF3CH(OH)(4-C6H4F) formed in catalysis, thus suggesting that diastereoisomeric alkoxides with the Ru-NH2 linkage are key species in the catalytic asymmetric transfer hydrogenation reaction.
机译：[RuCl-（CNN）（dppb））（1; HCNN = 6-（4-甲基苯基）-2-吡啶基甲胺）与NaOiPr在2-丙醇/ C6D6中的反应得到醇加合物醇盐[Ru（OiPr）-（ CNN）（dppb）]中心点niPrOH（5），包含Ru-NH2键。醇盐（Ru（OiPr）（CNN）（dppb）]（4）是通过在C6D6中用丙酮处理氢化物[Ru（H）（CNN）（dppb）]（2）形成的。络合物5在2-丙醇中/ C6D6在25°C下与氢化物2和丙酮快速平衡，交换速率为（5.4 +/- 0.2）s（-1），高于4到2（（2.9 +/- 0.4）s（- 1））。这种快速的过程涉及β-氢消除与酮插入Ru-H键之间，发生在Ru-NH2基序支持的氢键网络内。阳离子醇配合物[Ru（CNN）（dppb ）（iPrOH）]（BAr4f）（6; Ar-f = 3,5-C6H3-（CF3）（2）），由1，Na [BAr4f]和2-丙醇制得，与NaOiPr反应生成5。配合物5通过氢化物2与4,4'-二氟二苯甲酮反应或通过质子化与4,4'-二氟二苯甲酮反应，得到醇盐[Ru {OCH（4-C6H4F）（2）}（CNN）（dppb）]（7 ），分离出的产物的收率分别为90％和85％。手性CNN-钌化合物[RuCl（CNN）-{（S，S）-Skewphos}]（8），是通过[RuCl2（PPh3） （3）]在NEt3存在下具有（S，S）-Skewphos和HCNN的正金属化，是一种高活性催化剂，用于甲基芳基酮的对映选择性转移加氢（转换频率（TOFs）高达1.4 x 10（6））得到回流下的h（-1）），其ee高达89％。含有强吸电子CF3基团的酮CF3CO（4-C6H4F）也被还原为具有64％ee和TOF为1.5 x 10（4）h（-1）的R醇。在2-丙醇的存在下从8和NaOiPr获得的手性醇盐[Ru（OiPr）（CNN）-（S，S）-Skewphos）中心点niPrOH（9）与CF3CO-（4-C6H4F）反应得到非对映体醇盐[Ru {OCH-（CF3）（4-C6H4F）}（CNN）{（S，S）-Skewphos}]的混合物（10/11;产率74％），具有67％的de。该值非常接近催化过程中形成的醇（R）-CF3CH（OH）（4-C6H4F）的对映体过量，因此表明具有Ru-NH2键的非对映异构体醇盐是催化不对称转移氢化反应中的关键物质。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号