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lgq101木虫 (小有名气)
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[求助]
求翻译（有机合成）！！！~~~谢谢
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| Although translation to solid-phase synthesis was gratifyingly straightforward for most of these reactions, interesting differences from the original solution-phase results were noted in certain cases. For example, application of the Pauson–Khand reaction (19, 33, 34) to solid support-bound enynes 3 showed a slight trend toward higher yields and diastereoselectivities for the cyclopentapyrrolidinone products 5 in most cases (Scheme 3). This trend was particularly evident in the case of the phenyl-substituted product 5b (74% vs. 64% yield, 70∶30 vs. 50∶50 DR). Recognizing that the choice of solvent is known to affect this reaction in solution (35), we hypothesized that the polystyrene matrix might provide a more hydrophobic reaction milieu than suggested by the CH3CN solvent used to induce the cycloaddition reaction. Consistent with this idea, when the corresponding solution-phase reaction was carried out in benzene or toluene, similarly improved diastereoselectivities were observed. The diastereoselectivity of the solid-phase reaction could also be further improved by changing the solvent to benzene or toluene. This finding highlights the influence of the solid support in “solvent effects” on some reactions. |
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【答案】应助回帖
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lgq101(金币+20, 翻译EPI+1): 谢谢 2011-06-24 17:29:51
Mally89(金币+1): 感谢应助！~ 2011-06-24 21:36:20
lgq101(金币+20, 翻译EPI+1): 谢谢 2011-06-24 17:29:51
Mally89(金币+1): 感谢应助！~ 2011-06-24 21:36:20
| 虽然大多数反应转换到固相合成是令人满意的简单，但是在某些情况下结果与原本的溶液相反应存在着有趣的差异。例如，在大多数情况下，将Pauson - Khand反应（19，33，34）应用到固体支持的烯炔3上稍微地提高了cyclopentapyrrolidinone产品5的收率和立体选择性（图3）。这种趋势对于苯基取代的产品5B尤为明显（74与64％的收率，70:30与50:50 DR）。认识到溶剂的选择是此溶液反应众所周知的影响因素（35），我们推测，与用来诱导环加成反应的乙腈溶剂相比，聚苯乙烯基质可能会提供一个更加疏水的反应环境。与这个想法相符的是，当相应的溶液反应使用了苯或甲苯，同样提高了立体选择性。对于固相反应，通过使用苯或甲苯作溶剂，立体选择性也可以进一步提高。这一发现显示了固体载体的“溶剂效应”对一些反应的影响。 |
2楼2011-06-24 14:24:57