α-Tetrasubstituted Aldehydes through Electronic and Strain-Controlled Branch-Selective Stereoselective Hydroformylation.
α-Tetrasubstituted Aldehydes through Electronic and Strain-Controlled Branch-Selective Stereoselective Hydroformylation.
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DOI：
10.1021/acs.joc.8b01431
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发表时间：
2018-09-07
期刊：
影响因子：
--
通讯作者：
Schomaker JM
中科院分区：
文献类型：
--
作者：
Eshon J;Foarta F;Landis CR;Schomaker JM
加氢裂化利用二氢、一氧化碳和催化剂将烯烃转化为醛。本工作将手性双二氮磷杂环戊烷（BDP）和双磷杂环戊烷乙烷（BPE）配位的铑配合物应用于各种烯烃的加氢反应，生成手性四取代醛。带有吸电子取代基的1，1 ′-二取代的丙烯酸酯在温和条件（1摩尔%催化剂/BDP配体，150 psig气体，60 ℃）下进行加氢，具有高转化率和四取代醛（例如，13：1的区域选择性，85%ee，和对于1-氟甲基丙烯酸酯<1%的氢化）。该范围还包括无环1，1 ′-二取代和三取代的贫电子烯烃，以及由具有环外和环内不饱和度的小环组成的二取代和三取代烯烃。例如，1-亚甲基-β-内酰胺以98%的选择性和高达83%的ee提供四取代的醛。值得注意的是，手性三取代的双环亚甲基氮杂环丙烷以>99%的区域选择性和>19：1的非对映选择性转化为四取代的醛，速率>50催化剂周转/小时。HRh（BDP）（CO）2与甲基1-氟丙烯酸酯的非催化反应的NMR研究能够拦截叔烷基铑中间体，表明迁移插入到酰基物种比形成仲和伯烷基铑中间体慢。总体而言，这些研究揭示了如何利用空间、电子和环应变的相互作用，通过促进支链选择性加氢来提供有价值的α-四取代醛合成结构单元。
Hydroformylation utilizes dihydrogen, carbon monoxide, and a catalyst to transform alkenes into aldehydes. This work applies chiral bisdiazaphospholane (BDP) and bisphospholanoethane (BPE)-ligated rhodium complexes to the hydroformylation of a variety of alkenes to produce chiral tetrasubstituted aldehydes. 1,1’-Disubstituted acrylates bearing electron-withdrawing substituents undergo hydroformylation under mild conditions (1 mol% catalyst/BDP ligand, 150 psig gas, 60 °C) with high conversions and yields of tetrasubstituted aldehydes (e.g., 13:1 regioselectivity, 85% ee, and <1% hydrogenation for 1-fluoromethylacrylate). The scope also encompasses both acyclic 1,1’-disubstituted and trisubstituted, electron-poor alkenes, as well as di- and trisubstituted alkenes comprised of small rings with exocyclic and endocyclic unsaturation. For example, 1-methylene-β-lactam furnished the tetrasubstituted aldehyde with 98% selectivity and up to 83% ee. Notably, chiral trisubstituted bicyclic methyleneaziridines are transformed with >99% regioselectivity and >19:1 diastereoselectivity to tetrasubstituted aldehydes at rates >50 catalyst turnovers/hour. NMR studies of the non-catalytic reaction of HRh(BDP)(CO)2 with methyl 1-fluoroacrylate enable interception of tertiary alkyl-rhodium intermediates, demonstrating migratory insertion to acyl species is slower than formation of secondary and primary alkyl-rhodium intermediates. Overall, these investigations reveal how the interplay of sterics, electronics, and ring strain are harnessed to provide access to valuable α-tetrasubstituted aldehyde synthetic building blocks by promoting branched-selective hydroformylation.
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影响因子：
2.1
作者：
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通讯作者：
Chang, NC
影响因子：
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作者：
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影响因子：
--
作者：
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通讯作者：
PINNA, L