Rh(I)-Catalyzed [(3 + 2) + 1] Cycloaddition of 1-Yne/Ene-vinylcyclopropanes and CO: Homologous Pauson−Khand Reaction and Total Synthesis of (±)-α-Agarofuran
作者:Lei Jiao、Mu Lin、Lian-Gang Zhuo、Zhi-Xiang Yu
DOI:10.1021/ol100625e
日期:2010.6.4
A novel Rh(I)-catalyzed [(3 + 2) + 1] cycloaddition, which can be regarded as a homologous Pauson-Khand reaction, was developed to synthesize bicyclic cyclohexenones and cyclohexanones, enabling a new approach for synthesis of six-membered carbocycles ubiquitously found in natural products and pharmaceutics. The significance of the Rh-catalyzed [(3 + 2) + 1] cycloaddition has been demonstrated by the total synthesis of a furanoid sesquiterpene natural product, a-agarofuran, in which the bicyclic skeleton was constructed by the [(3 + 2) + 1] reaction of 1-yne-VCP and CO.
Dual Activation Strategy to Achieve C–C Cleavage of Cyclobutanes: Development and Mechanism of Rh and Zn Cocatalyzed [4 + 2] Cycloaddition of Yne-Vinylcyclobutanones
newly designed yne-vinylcyclobutanones, which can generate 5/6 or 6/6 bicyclic products with an all-carbonquaternary bridgehead center. The reaction has a broad scope and can realize chirality transfer from enantioenriched substrates to the cycloadducts. The key to the success of this [4 + 2] reaction is the introduction of a vinyl group to cyclobutanones, which helps the C–C cleavage of vinylcyclobutanones