Diels−Alder Reactions of Amino Acid-Derived Trienes
Diels−Alder Reactions of Amino Acid-Derived Trienes
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氨基酸衍生三烯的 Diels−Alder 反应
DOI：
10.1021/jo990459f
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发表时间：
1999
影响因子：
3.6
通讯作者：
A. Gauthier
中科院分区：
文献类型：
--
作者：
W. Murray;Sengen Sun;I. Turchi;A. J. K. Brown;A. Gauthier
构建了三烯前体（1a−e, 2a−k）用于底物控制的不对称Diels−Alder反应。将boc -l-苯丙醛和boc -l-缬醛与三乙基磷酸乙酸酯或2-磷酸丙酸缩合生成亲二酚类α，β-不饱和酯。去除Boc基团得到游离胺4a−d，在n -苄基化或未n -苄基化后，用3,5-六烯酰氯处理得到1a−e，或用2,4-六烯酰氯处理得到2a−f。通过胺4a - i与2,4-己二醛的还原烷基化反应制备了三烯化合物2g - i。在170°C加热时，仲酰胺三烯1a不能产生任何Diels−Alder产物。叔酰胺三烯1b−e在回流甲苯中产生了顺式融合的主要环加成产物，并从外过渡态衍生。三烯2a−k发生了令人惊讶的简单Diels−Alder反应，产生了主要的跨融合异构体，这些异构体来源于内端过渡态。对于三烯2b - h和2j，k， Diels - Alder反应过程…
Triene precursors (1a−e, 2a−k) were constructed for substrate-controlled asymmetric Diels−Alder reactions. Boc-l-phenylalanal and Boc-l-valinal were condensed with triethyl phosphonoacetate or 2-phosphonopropionate to generate the α,β-unsaturated esters as dienophiles. Removal of the Boc group to give free amines 4a−d, which after, or without N-benzylation, were treated with 3,5-hexadienoyl chloride to give 1a−e, or with 2,4-hexadienoyl chloride to afford 2a−f. The trienes 2g−i were prepared via reductive alkylation of amines 4a−i with 2,4-hexadienal. The secondary amide triene 1a failed to yield any Diels−Alder product when heated at 170 °C. The tertiary amide trienes 1b−e produced in refluxing toluene the major cycloaddition products that were cis-fused and derived from the exo transition states. Trienes 2a−k underwent surprisingly facile Diels−Alder reactions to produce the major trans-fused isomers that were derived from the endo transition states. For trienes 2b−h and 2j,k, Diels−Alder reactions proc...