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lgq101

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[求助] 求翻譯（有機(jī)合成）！��！~~~謝謝

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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1樓 2011-06-24 12:52:13

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lgq101(金幣+20, 翻譯EPI+1): 謝謝 2011-06-24 17:29:51
Mally89(金幣+1): 感謝應(yīng)助！~ 2011-06-24 21:36:20

雖然大多數(shù)反應(yīng)轉(zhuǎn)換到固相合成是令人滿意的簡(jiǎn)單，但是在某些情況下結(jié)果與原本的溶液相反應(yīng)存在著有趣的差異。例如，在大多數(shù)情況下，將Pauson - Khand反應(yīng)（19，33，34）應(yīng)用到固體支持的烯炔3上稍微地提高了cyclopentapyrrolidinone產(chǎn)品5的收率和立體選擇性（圖3）。這種趨勢(shì)對(duì)于苯基取代的產(chǎn)品5B尤為明顯（74與64％的收率，70:30與50:50 DR）。認(rèn)識(shí)到溶劑的選擇是此溶液反應(yīng)眾所周知的影響因素（35），我們推測(cè)，與用來誘導(dǎo)環(huán)加成反應(yīng)的乙腈溶劑相比，聚苯乙烯基質(zhì)可能會(huì)提供一個(gè)更加疏水的反應(yīng)環(huán)境。與這個(gè)想法相符的是，當(dāng)相應(yīng)的溶液反應(yīng)使用了苯或甲苯，同樣提高了立體選擇性。對(duì)于固相反應(yīng)，通過使用苯或甲苯作溶劑，立體選擇性也可以進(jìn)一步提高。這一發(fā)現(xiàn)顯示了固體載體的“溶劑效應(yīng)”對(duì)一些反應(yīng)的影響。

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2樓2011-06-24 14:24:57

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