A systematic study of the effects of relative configuration, protecting group, and enolate type on the diastereoselectivities of aldol reactions of a chiral ethyl ketone with 2-methylpropanal.
A systematic study of the effects of relative configuration, protecting group, and enolate type on the diastereoselectivities of aldol reactions of a chiral ethyl ketone with 2-methylpropanal.
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系统研究相对构型、保护基团和烯醇化物类型对手性乙基酮与 2-甲基丙醛的羟醛反应的非对映选择性的影响。
DOI：
10.1021/jo500927x
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Sushital Jana
中科院分区：
文献类型：
--
作者：
D. E. Ward;Diptarghya Kundu;M. Biniaz;Sushital Jana
本文报道了2-甲基丙醛与6-（2-乙基-1，3-二氧戊环-2-基）-5-羟基-4-甲基庚-3-酮的四种外消旋非对映体的5-O-甲氧基甲基和5-O-三乙基甲硅烷基衍生物的各种烯醇化物的羟醛缩合反应的非对映选择性。（E）-烯醇二环己基硼酸酯、（Z）-烯醇9-BBN硼酸酯（即，9-（（Z）-烯氧基）-9-硼双环[3.3.1]壬烷）、Li（E）-烯醇化物、Li（Z）-烯醇化物和Ti（IV）（Z）-烯醇化物。硼和Li烯醇化物通过标准方法制备，但Ti（IV）烯醇化物通过Li（Z）-烯醇化物与TiCln（Oi-Pr）（4-n）（n = 0-2）反应的金属转移而获得。羟醛的相对位置性（简单的非对映选择性）与烯醇化物的几何形状密切相关：来自（E）-烯醇化物的反羟醛和来自（Z）-烯醇化物的顺羟醛。然而，对于每种烯醇化物类型，非对映体选择性随着8种起始酮中C5保护基的相对构型和性质而广泛变化（5-400倍）。合理的过渡态模型假设合理化这些意见。通过对由相应的5，7-syn二醇制备的12种丙酮衍生物的NMR分析，证实了16种非对映异构体2-（2-乙基-1，3-二氧戊环-2-基）-7-羟基-3-（甲氧基甲氧基）-4，6，8-三甲基壬-5-酮羟醛加合物的完整集合的相对构型。对上述羟醛加合物组的NMR数据的检查揭示了一致的趋势，利用这些趋势来指定1,3种非对映异构体2-（2-乙基-1，3-二氧戊环-2-基）-7-羟基-3-（三乙基甲硅烷氧基）-4，6，8-三甲基壬-5-酮羟醛加合物的相对构型。
The diastereoselectivities of aldol reactions of 2-methylpropanal with various enolates of 5-O-methoxymethyl and 5-O-triethylsilyl derivatives of the four racemic diastereomers of 6-(2-ethyl-1,3-dioxolan-2-yl)-5-hydroxy-4-methylheptan-3-one are reported. Reactions of the (E)-enol dicyclohexylborinates, (Z)-enol 9-BBN borinates (i.e., 9-((Z)-enoxy)-9-borabicyclo[3.3.1]nonanes), Li (E)-enolates, Li (Z)-enolates, and Ti(IV) (Z)-enolates were examined. Boron and Li enolates were prepared by standard methods, but Ti(IV) enolates were obtained via transmetalation of the Li (Z)-enolates by reaction with TiCln(Oi-Pr)(4-n) (n = 0-2). Aldol relative topicity (simple diastereoselectivity) was strongly correlated to the enolate geometry: anti aldols from (E)-enolates and syn aldols from (Z)-enolates. However, for each enolate type, the diastereoface selectivities varied widely (by factors of 5-400) with the relative configuration and nature of the C5 protecting group in the 8 starting ketones. Plausible transition state models are postulated to rationalize some of these observations. The relative configurations for the complete set of 16 diastereomeric 2-(2-ethyl-1,3-dioxolan-2-yl)-7-hydroxy-3-(methoxymethoxy)-4,6,8-trimethylnonan-5-one aldol adducts were confirmed by NMR analysis of 12 acetonide derivatives prepared from the corresponding 5,7-syn diols. Examination of the NMR data for the above set of aldol adducts revealed consistent trends that were exploited to assign the relative configurations of 13 diastereomeric 2-(2-ethyl-1,3-dioxolan-2-yl)-7-hydroxy-3-(triethylsilyloxy)-4,6,8-trimethylnonan-5-one aldol adducts.
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利用硅杂环丙烷作为合成中间体合成(i-)-表-stegobinone。
DOI：
10.1021/jo0620011
发表时间：
2007
期刊：
The Journal of organic chemistry
影响因子：
--
作者：
Calad,StacieA;Cirakovic,Jelena;Woerpel,KA
通讯作者：
Woerpel,KA
影响因子：
5.2
作者：
More, JD;Finney, NS
通讯作者：
Finney, NS
影响因子：
16.6
作者：
Jung, Michael E.;Salehi-Rad, Ramin
通讯作者：
Salehi-Rad, Ramin
使用非醇醛醇醛-铜酸酯开环工艺全合成金吡喃酮 B。
影响因子：
5.2
作者：
Jung,MichaelE;Chaumontet,Manon;Salehi-Rad,Ramin
通讯作者：
Salehi-Rad,Ramin