Transformations of Less-Activated Phenols and Phenol Derivatives via C-O Cleavage.,Chemical Reviews

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Transformations of Less-Activated Phenols and Phenol Derivatives via C-O Cleavage.
Chemical Reviews ( IF 51.4 ) Pub Date : 2020-08-28 , DOI: 10.1021/acs.chemrev.0c00088
Zihang Qiu ₁ , Chao-Jun Li ₁

Affiliation

Employing phenols and phenol derivatives as electrophiles for cross-coupling reactions has numerous advantages over commonly used aryl halides in terms of environmental-friendliness and sustainability. In the early stage of discovering such transformations, most efforts have been devoted to utilizing highly activated sulfonate types of phenol derivatives (e.g., OTf, OTs, etc.), which have similar reactivities to the corresponding aryl halides. However, a continuing scientific challenge is how to achieve the direct C–O functionalizations of relatively less-activated phenol derivatives more efficiently. In this review, we will focus on the recent updates on the C–O functionalizations of less-activated phenol derivatives, from aryl carboxylates (e.g., pivalates, acetates, etc.), aryl carbamates and carbonates, to aryl ethers (anisoles, diaryl ethers, aryl pyridyl ethers, aryl silyl ethers), to phenolate salts, and ultimately to simply unprotected phenols, sorted by the types of bond formations. Both transition-metal-catalyzed and transition-metal-free protocols will be covered and discussed in detail. Instead, the C–O functionalizations of aryl sulfonates will not be covered extensively unless they are closely related, due to their high reactivity. Since aryl ethers and phenols represent the main linkages or units in lignin biomass, the successes of such transformations will potentially make major contributions to the direct lignin biomass upgrading and depolymerization.

中文翻译：

较少活化的苯酚和苯酚衍生物通过CO裂解的转化。

就环境友好性和可持续性而言，与常用的芳基卤化物相比，采用酚和酚衍生物作为亲电试剂进行交叉偶联反应具有许多优势。在发现此类转化的早期，大多数努力已致力于利用具有与相应的芳基卤化物相似的反应性的高度活化的磺酸盐类型的苯酚衍生物（例如，OTf，OTs等）。然而，一个持续的科学挑战是如何更有效地实现相对较少活化的苯酚衍生物的直接C-O功能化。在这篇综述中，我们将关注活化程度较低的苯酚衍生物的C–O功能化的最新进展，从芳基羧酸盐（例如新戊酸酯，乙酸盐等），氨基甲酸酯和碳酸盐到芳醚（苯甲醚，二芳基醚，芳基吡啶基醚，芳基甲硅烷基醚）生成酚盐，最终生成简单的未保护酚，并按键形成类型进行分类。过渡金属催化的方案和无过渡金属的方案都将进行讨论。相反，由于它们的高反应性，除非它们密切相关，否则芳基磺酸盐的C–O官能化将不会被广泛涉及。由于芳基醚和酚代表木质素生物质中的主要键或单元，因此这种转化的成功将对木质素生物质的直接升级和解聚做出重大贡献。过渡金属催化的方案和无过渡金属的方案都将进行讨论。相反，由于它们的高反应性，除非它们紧密相关，否则芳基磺酸盐的C–O官能化将不会被广泛涉及。由于芳基醚和酚代表木质素生物质中的主要键或单元，因此这种转化的成功将对木质素生物质的直接升级和解聚做出重大贡献。过渡金属催化的方案和无过渡金属的方案都将进行讨论。相反，由于它们的高反应性，除非它们紧密相关，否则芳基磺酸盐的C–O官能化将不会被广泛涉及。由于芳基醚和酚代表木质素生物质中的主要键或单元，因此这种转化的成功将对木质素生物质的直接升级和解聚做出重大贡献。

更新日期：2020-09-23

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