Alcaide Benito, Almendros Pedro, Martínez del Campo Teresa, Soriano Elena, Marco-Contelles José L
Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Chemistry. 2009 Sep 14;15(36):9127-38. doi: 10.1002/chem.200901180.
Regiocontrolled metal-catalyzed preparations of enantiopure dihydropyrans and tetrahydrooxepines have been synthesized starting from beta- and gamma-allenols derived from D-glyceraldehyde. The Pd(II)-catalyzed cyclizative coupling reactions of beta-allenols 1 a and 1 b with allyl bromide effectively afforded enantiopure tetrafunctionalized dihydropyrans through a 6-endo oxycyclization protocol, whereas the gold-, platinum-, and palladium-mediated heterocyclization of gamma-allenol 2 furnished tetrahydrooxepines 13-16 through regioselective 7-endo-trig oxycyclization reactions. Moreover, density functional calculations were performed to predict the regioselectivity of the gamma-allenol cycloetherification to tetrahydrooxepines on the basis of both the tether nature and characteristics of the metals, and to gain an insight into the mechanism of the oxycyclization reactions.
已经从D-甘油醛衍生的β-和γ-烯丙醇开始，合成了对映体纯的二氢吡喃和四氢氧杂环庚烷的区域控制金属催化制剂。β-烯丙醇1a和1b与烯丙基溴的钯（II）催化的环化偶联反应通过6-内型氧环化方案有效地提供了对映体纯的四官能化二氢吡喃，而γ-烯丙醇2的金、铂和钯介导的杂环化通过区域选择性7-内型-三取代氧环化反应提供了四氢氧杂环庚烷13-16。此外，进行了密度泛函计算，以基于连接链的性质和金属的特性预测γ-烯丙醇环醚化生成四氢氧杂环庚烷的区域选择性，并深入了解氧环化反应的机理。
