Ruthenium-catalyzed cis-dihydroxylation of alkenes: Scope and limitations
Ruthenium-catalyzed cis-dihydroxylation of alkenes: Scope and limitations
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DOI：
10.1002/chem.19960020111
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发表时间：
1996-01-01
影响因子：
4.3
通讯作者：
Jiang, Q
中科院分区：
文献类型：
--
作者：
Shing, TKM;Tam, EKW;Jiang, Q
氧化钌催化（0.07 摩尔当量 RuCl3 . (H2O)(3)、1.5 摩尔当量 NaIO4、EtOAc/CH3CN/H2O 3:3:1），超出了通常的 C-C 键断裂产生二羰基的范围，已被证明可以对多种烯烃进行顺式二羟基化（除紧张的双环烯烃外，空间上位阻三取代烯烃和大多数四取代烯烃）可快速（在几分钟内）有效地生成邻位二醇。次要产物是常见的氧化裂变产物，即酮和醛或羧酸，有时还有酮醇。较长的反应时间会降低大多数二醇的产率，这可能是由于氧化乙二醇裂解所致。与含有一个或多个与烯烃部分共轭或邻近的吸电子基团的底物的反应通常较慢，但产生更好的产率。本发明的“闪速”二羟基化（针对现有的α-立体中心）与环烯烃的非对映选择性非常好，而与无环烯烃的非对映选择性是中度至差。偏高碘酸钠仍然是催化反应最好的助氧化剂。人们发现，在某些情况下，作为替代溶剂系统的乙腈水溶液（约 86%）比原始溶剂系统能提供更高的 1,2-二醇产率。
Oxidative ruthenium catalysis (0.07 mol-equiv RuCl3 . (H2O)(3), 1.5 mol-equiv NaIO4, EtOAc/CH3CN/H2O 3:3:1), beyond the usual C-C bond cleavage to give dicarbonyls, has been shown to syn-dihydroxylate a wide range of alkenes (except for strained bicyclic alkenes, sterically hindered trisubstituted alkenes, and most tetrasubstituted alkenes) to give vicinal diols rapidly (within minutes) and efficiently. The minor products are the usual oxidative fission products, namely, ketones and aldehydes or carboxylic acids, and sometimes ketols. Longer reaction times lower the yields of most diols, probably owing to oxidative glycol cleavage. Reactions with substrates containing one or more electron-withdrawing groups in conjugation with or adjacent to the alkene moiety are generally slower but give better yields. The diastereoselectivity of the present ''flash'' dihydroxylation, anti to the existing alpha-stereogenic center, with cycloalkenes is excellent whereas that with acyclic alkenes is moderate to poor. Sodium metaperiodate is still the best co-oxidant for the catalytic reaction. Aqueous acetonitrile (approximately 86%) as an alternative solvent system was found to give better yields of 1,2-diols than the original solvent system in some cases.