Rhodium-Catalyzed [2+2+2] Cycloaddition Reactions of Linear Allene-Ene-Ynes to afford Fused Tricyclic Scaffolds: Insights into the Mechanism
Rhodium-Catalyzed [2+2+2] Cycloaddition Reactions of Linear Allene-Ene-Ynes to afford Fused Tricyclic Scaffolds: Insights into the Mechanism
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DOI：
10.1002/chem.201703194
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发表时间：
2017-10-20
影响因子：
4.3
通讯作者：
Roglans, Anna
中科院分区：
文献类型：
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作者：
Cassu, Daniel;Parella, Teodor;Roglans, Anna
合成了丙二烯-（E）-烯-炔N-对甲苯磺酰基栓系底物3a-3 h，并对其铑催化的[2+2+2]环加成反应进行了评价。环加成是化学选择性的，因为只有丙二烯的近端双键反应以提供稠合三环支架中的环外双键。立体选择性取决于所使用的催化体系。首次采用密度泛函理论计算研究了联烯、烯烃和炔之间的反应性。这种机理研究确定了不饱和基团参与催化循环的顺序。
Allene-(E)-ene-yne N-tosyl-tethered substrates 3a-3h were efficiently prepared and their rhodium-catalyzed [2+2+2] cycloaddition reactions were evaluated. The cycloadditions are chemoselective as only the proximal double bond of the allene reacted to afford exocyclic double bonds in the fused-tricyclic scaffolds. The stereoselectivity depended on the catalytic system used. Reactivity between allene, alkene, and alkyne was studied for the first time by density functional theory calculations. This mechanistic study determines the order in which the unsaturated groups take part in the catalytic cycle.