Regio- and diastereoselective tandem rhodium-catalyzed allylic alkylation Pauson-Khand annulation reactions
Regio- and diastereoselective tandem rhodium-catalyzed allylic alkylation Pauson-Khand annulation reactions
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DOI：
10.1021/ja015531h
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发表时间：
2001-05-16
影响因子：
15
通讯作者：
Robinson, JE
中科院分区：
文献类型：
--
作者：
Evans, PA;Robinson, JE
利用过渡金属催化的成环反应构建复杂的多环体系为靶向合成提供了一个强有力的策略。[1] Pauson-Khand（PK）环化反应是这类转化的代表，其中栓系烯炔进行形式[2+ 2+ 1]反应，得到双环环戊烯酮。2，3该方法的一个重要限制是为了抑制竞争性分子间金属催化反应而需要分子内。然而，最近的研究提供了一种新的方法来解决这个问题，它利用双催化体系，以促进一锅钯催化烯丙基烷基化，然后铑催化PK成环反应。4我们设想了一种解决这个问题的替代方法，该方法利用单一金属催化剂来促进串联序列中的两种转化，仅使用反应温度来调节催化活性。该策略的明显优点是通过在C-2处引入立体中心显著增加双环加合物的分子复杂性的能力，我们预期这将控制PK环化中的非对映选择性。在本文中，我们现在描述使用稳定的碳和杂原子亲核试剂的区域选择性和非对映选择性铑催化的串联烯丙基烷基化/Pauson-Khand成环反应的开发（等式1）。
The construction of complex polycyclic systems using transition metal-catalyzed annulation reactions provides a powerful strategy for target directed synthesis. 1 The Pauson-Khand (PK) annulation is representative of this class of transformations in which a tethered eneyne undergoes a formal [2+ 2+ 1] reaction to furnish a bicyclic cyclopentenone. 2, 3 A significant limitation with this process is the necessity for intramolecularity in order to suppress competitive intermolecular metal-catalyzed reactions. However, a recent study provided a new approach to this problem, which utilized a dual catalytic system to facilitate a one-pot palladium-catalyzed allylic alkylation followed by a rhodiumcatalyzed PK annulation reaction. 4 We envisioned an alternative approach to this problem that utilized a single metal-catalyst to facilitate both transformations in a tandem sequence, using only the reaction temperature to modulate the catalytic activity. The obvious advantage of this strategy was the ability to significantly increase the molecular complexity of the bicyclic adduct through the introduction of a stereogenic center at C-2, which we anticipated would control diastereoselectivity in the PK annulation. 5 Herein, we now describe the development of the regio-and diastereoselective rhodium-catalyzed tandem allylic alkylation/Pauson-Khand annulation reaction using stabilized carbon and heteroatom nucleophiles (eq 1).