Department of Chemistry, Indian Institute of Technology, Hyderabad, Ordnance Factory Estate Campus, Yeddumailaram - 502 205, Medak District, Andhra Pradesh, India.
Org Lett. 2012 Jan 20;14(2):628-31. doi: 10.1021/ol2032625. Epub 2012 Jan 11.
An efficient Pd-catalyzed domino reaction of α,α-dialkyl-(2-bromoaryl)methanols to 6,6-dialkyl-6H-benzo[c]chromenes is presented. Their formation can be explained via a five membered Pd(II)-cycle that efficiently involves a domino homocoupling with the second molecule, β-carbon cleavage, and finally intramolecular Buchwald-Hartwig cyclization. This domino process effectively involves breaking of five σ-bonds (2C-Br, 2O-H, and a C-C) and formation of two new σ-bonds (C-C and C-O). This mechanistic pathway is unprecedented and further illustrates the power of transition metal catalysis.
本文报道了一种高效的钯催化的α,α-二烷基-(2-溴芳基)甲醇的级联反应，生成 6,6-二烷基-6H-苯并[c]色烯。其形成可以通过一个五元的 Pd(II)环来解释，该环有效地涉及到与第二个分子的串联偶联、β-碳裂解，以及最后分子内的 Buchwald-Hartwig 环化。这个级联过程有效地涉及到五个σ键（2C-Br、2O-H 和一个 C-C）的断裂和两个新的σ键（C-C 和 C-O）的形成。这种反应机制是前所未有的，进一步说明了过渡金属催化的强大威力。
