The substituted cyclopentenone unit is a common scaffold in numerous natural products and pharmaceuticals. As well, the cyclopentene moiety is also an important functional group in the prostaglandins (PGs). For example, prostaglandin analogs (PGAs) have long been known to be involved in the control of renal function, hormone regulation, and vasoand broncho-dilatation. Moreover, these scaffolds are useful as agricultural chemicals, perfumes and as general intermediates in organic synthesis. The a,b-unsaturated carbonyl structure is crucial in such varied biological processes as the inhibition of tumors, viruses and inflammation. Several methodologies for the synthesis of substituted cyclopentenones have thus been reported; these have included the Nazarov cyclization, the Pauson-Khand reaction and the use of metal-carbonyl complexes. However, given their significance, there is still considerable room for improvement in the preparation of these compounds. As background, we noted that using the reagent Cp2ZrCl2/2EtMgBr together with 1-alkynylboronates leads to the regioselective formation of zirconacyclopentene boronate intermediates of Type 3 (Scheme 1). Syntheses of cyclopentenone boronates are yet to be reported, but these structures would be highly valued intermediates in organic synthesis and could be useful partners in such cross-coupling reactions as the SuzukiMiyaura coupling. Herein we report for the first time the synthesis of cyclopentenone boronic acids under mild conditions using a simple work-up. The present method gives excellent results and offers a direct method for the synthesis of functionalized cyclopentenones. A number of zirconacyclopentenylboronates were treated with oxalyl chloride in THF at 0 C to yield the corresponding cyclopentenone boronic acids (Table 1, Table 2). Thus, alkyne boronate 2a prepared by borylation of 1-heptyne (Table 1) was chosen as a model to test our hypothesis. The zirconacyclopentenylboronate Type 3 intermediate was prepared by reacting two equivalents of the Cp2ZrCl2/2EtMgBr reagent with the 1-alkynylboronate. We found an efficient system for the desired transformation to 4a could be made from the combination of CuCl catalyst in the presence of N,N’-

中文翻译：

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通过 α-Borylzirconacyclopentene 中间体合成取代环戊烯酮的一般方法

取代的环戊烯酮单元是许多天然产物和药物中的常见支架。同样，环戊烯部分也是前列腺素 (PG) 中的一个重要官能团。例如，长期以来已知前列腺素类似物 (PGA) 参与肾功能的控制、激素调节以及血管和支气管扩张。此外，这些支架可用作农药、香料和有机合成中的一般中间体。a,b-不饱和羰基结构在抑制肿瘤、病毒和炎症等多种生物过程中至关重要。因此已经报道了几种合成取代环戊烯酮的方法；其中包括 Nazarov 环化、Pauson-Khand 反应和金属-羰基配合物的使用。然而，鉴于它们的重要性，这些化合物的制备仍有相当大的改进空间。作为背景，我们注意到将试剂 Cp2ZrCl2/2EtMgBr 与 1-炔基硼酸酯一起使用会导致区域选择性形成 3 型氧化锆环戊烯硼酸酯中间体（方案 1）。环戊烯酮硼酸酯的合成还有待报道，但这些结构将是有机合成中非常有价值的中间体，并且可能是诸如 SuzukiMiyaura 偶联等交叉偶联反应的有用伙伴。在此，我们首次报道了在温和条件下使用简单的后处理合成环戊烯酮硼酸。本方法给出了极好的结果，并提供了一种合成功能化环戊烯酮的直接方法。在 0°C 下，在 THF 中用草酰氯处理许多锆基环戊烯基硼酸酯以产生相应的环戊烯酮硼酸（表 1、表 2）。因此，选择通过 1-庚炔硼酸化制备的炔烃硼酸酯 2a（表 1）作为模型来测试我们的假设。通过使两当量的 Cp2ZrCl2/2EtMgBr 试剂与 1-炔基硼酸酯反应制备 3 型锆碳环戊烯基硼酸酯中间体。我们发现，在 N,N'- 存在下，CuCl 催化剂的组合可以制成用于所需转化为 4a 的有效系统 通过使两当量的 Cp2ZrCl2/2EtMgBr 试剂与 1-炔基硼酸酯反应制备 3 型锆碳环戊烯基硼酸酯中间体。我们发现，在 N,N'- 存在下，CuCl 催化剂的组合可以制成用于所需转化为 4a 的有效系统 通过使两当量的 Cp2ZrCl2/2EtMgBr 试剂与 1-炔基硼酸酯反应制备 3 型锆碳环戊烯基硼酸酯中间体。我们发现，在 N,N'- 存在下，CuCl 催化剂的组合可以制成一个有效的系统，用于所需的 4a 转化