Computation-guided development of Au-catalyzed cycloisomerizations proceeding via 1,2-Si or 1,2-H migrations: regiodivergent synthesis of silylfurans.
Computation-guided development of Au-catalyzed cycloisomerizations proceeding via 1,2-Si or 1,2-H migrations: regiodivergent synthesis of silylfurans.
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DOI：
10.1021/ja910290c
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发表时间：
2010-06-09
影响因子：
15
通讯作者：
Gevorgyan V
中科院分区：
文献类型：
--
作者：
Dudnik AS;Xia Y;Li Y;Gevorgyan V
借助密度泛函理论计算，设计了一种新的高效的区域发散Au催化的联烯基酮和高炔丙基酮环化异构化反应.这种级联转化的特征是常见金卡宾中间体中的1，2-Si或1，2-H迁移。实验和计算结果都清楚地表明，在β-Si取代的Au卡宾中，1，2-Si的迁移比H、烷基和芳基的1，2-迁移更有利。此外，Au（I）催化的高炔丙基酮环异构化反应的实验结果表明，反离子和溶剂效应可以逆转上述迁移选择性。DFT计算为这种1，2-迁移区域差异性提供了理论依据。因此，在AuSbF 6 −的情况下，DFT模拟的反应通过最初的炔丙基-丙二烯基异构化，然后环化成Au-卡宾中间体，只形成1，2-Si迁移产物，溶剂效应不会影响这种区域选择性。然而，在TfO−-配合物的情况下，反应通过最初的5-endo-dig环化发生，得到环状呋喃基-Au中间体。在非极性溶剂的情况下，后者的随后ipso-protiodeauration是动力学上更有利的比常见的Au-卡宾中间体的生成，并导致形成正式的1，2-H迁移产物。相比之下，当极性溶剂用于该DFT模拟的反应中时，呋喃基-Au物种的β-至-Au质子化以得到Au-卡宾中间体与自身质子化去质子化竞争。随后的解离的三氟甲磺酸酯配体在极性介质中，由于有效的溶剂化带电的中间体促进形成的1，2-Si移位产品。实验数据验证了DFT计算结果的正确性。本研究表明，DFT计算可以有效地支持实验结果，为合理设计新的催化转化提供指导。
A novel highly efficient regiodivergent Au-catalyzed cycloisomerization of allenyl- and homopropargylic ketones into synthetically valuable 2- and 3-silylfurans has been designed with the aid of the DFT calculations. This cascade transformation features 1,2-Si- or 1,2-H migrations in a common Au-carbene intermediate. Both experimental and computational results clearly indicate that the 1,2-Si migration is kinetically favored over the 1,2-shifts of H, alkyl, and aryl groups in the β-Si-substituted Au-carbenes. In addition, experimental results on the Au(I)-catalyzed cycloisomerization of homopropargylic ketones demonstrated that counterion and solvent effects could reverse the above migratory preference. The DFT calculations provided a rationale for this 1,2-migration regiodivergency. Thus, in the case of AuSbF6−, DFT-simulated reaction proceeds through the initial propargyl-allenyl isomerization followed by the cyclization into the Au-carbene intermediate with the exclusive formation of 1,2-Si migration products and solvent effects cannot affect this regioselectivity. However, in the case of TfO−-counterion, reaction occurs via the initial 5-endo-dig cyclization to give cyclic furyl-Au intermediate. In the case of nonpolar solvents, subsequent ipso-protiodeauration of the latter is kinetically more favorable than the generation of the common Au-carbene intermediate and leads to the formation of formal 1,2-H migration products. In contrast, when polar solvent is employed in this DFT-simulated reaction, β-to-Au protonation of the furyl-Au species to give Au-carbene intermediate competes with the ipso-protiodeauration. Subsequent dissociation of the triflate ligand in this carbene in polar media due to efficient solvation of charged intermediates facilitates formation of the 1,2-Si shift products. The above results of DFT calculations were validated by the experimental data. The present study demonstrates that the DFT calculations could efficiently support experimental results, providing guidance for rational design of new catalytic transformations.
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影响因子：
15
作者：
Comas-Vives, A;González-Arellano, C;Ujaque, G
通讯作者：
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影响因子：
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影响因子：
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作者：
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影响因子：
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作者：
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