Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Mohali, Manauli P.O., Punjab, 140306, India.
Org Biomol Chem. 2023 Feb 22;21(8):1793-1813. doi: 10.1039/d2ob02322a.
In this paper, we report a synthetic protocol for the construction of biaryl motif-based or π-extended azobenzene and alkylated azobenzene derivatives the Pd(II)-catalyzed bidentate directing group (DG)-aided C-H activation and functionalization strategy. In the past, the synthesis of biaryl motif-based azobenzenes was accomplished through the traditional cross-coupling reaction involving organometallic reagents and aryl halides or equivalent coupling partners. We have shown the direct coupling of C-H bonds of aromatic/aliphatic carboxamides (possessing a DG) with iodoazobenzenes as the coupling partners through the Pd(II)-catalyzed bidentate DG-aided, site-selective C-H functionalization method. Azobenzene-containing compounds are a versatile class of photo-responsive molecules that have found applications across branches of chemical, biological and materials sciences and are prevalent in medicinally relevant molecules. Accordingly, the synthesis of new and functionalized azobenzene-based scaffolds has been an attractive topic of research. Although the classical methods are efficient, they need pre-functionalized starting materials. This protocol involving the Pd(II)-catalyzed, directing group-aided site-selective C-H arylation of aromatic and aliphatic carboxamides using iodoazobenzene as the coupling partner affording azobenzene-based carboxamides is an additional route and also a contribution towards enriching the library of modified azobenzenes. We have also shown the photoswitching properties of representative compounds synthesized the Pd(II)-catalyzed directing group-aided site-selective C-H functionalization method.
在本文中，我们报告了一种基于联芳基基元和π-扩展偶氮苯以及烷基化偶氮苯衍生物的合成方案，该方案采用 Pd(II)催化的双齿导向基团 (DG)辅助 C-H 活化和官能化策略。在过去，基于联芳基基元的偶氮苯的合成是通过传统的交叉偶联反应完成的，该反应涉及有机金属试剂和芳基卤化物或等效的偶联伙伴。我们已经展示了通过 Pd(II)催化的双齿 DG 辅助、位点选择性 C-H 功能化方法，直接偶联芳基/脂肪族酰胺（具有 DG）的 C-H 键与碘代偶氮苯作为偶联伙伴。含偶氮苯的化合物是一类多功能的光响应分子，已在化学、生物和材料科学的各个分支中得到应用，并且在与医学相关的分子中很常见。因此，合成新的和功能化的偶氮苯基支架一直是一个有吸引力的研究课题。尽管经典方法效率高，但它们需要预官能化的起始材料。本方案涉及使用碘代偶氮苯作为偶联伙伴，通过 Pd(II)催化的导向基团辅助的芳基和脂肪族酰胺的位点选择性 C-H 芳基化反应，合成偶氮苯基酰胺，这是一种额外的途径，也是丰富修饰偶氮苯库的一种贡献。我们还展示了通过 Pd(II)催化的导向基团辅助的位点选择性 C-H 功能化方法合成的代表性化合物的光致变色性质。
