Toward calix[2]-type macrocycles: Synthesis and structural analysis of cyclic tetraketone and highly strained?furanophane
Toward calix[2]-type macrocycles: Synthesis and structural analysis of cyclic tetraketone and highly strained?furanophane
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面向杯[2]型大环化合物：环四酮和高张力呋喃芬的合成和结构分析
DOI：
10.1142/s1088424623500189
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发表时间：
2023
影响因子：
1.5
通讯作者：
Inokuma Yasuhide
中科院分区：
文献类型：
--
作者：
Sano Taichi;Sun Yuhua;Mukai Taichi;Inaba Yuya;Yoneda Tomoki;Ide Yuki;Pirillo Jenny;Hijikata Yuh;Inokuma Yasuhide
杯[3]吡咯合成的最新进展表明，以3，3-二烷基化戊烷-2，4-二酮为重复单元的环状聚酮是制备应变杯[3]吡咯大环化合物的理想前体。杯[2]吡咯和杯[2]呋喃是杯[1]吡咯和杯[2]呋喃中最具张力的同系物，为了合成杯[1]吡咯和杯[2]呋喃，我们报道了3，3-二甲基戊烷-2，4-二酮的环状二聚体及其呋喃衍生物的合成。这些化合物由线性四酮前体制备。单晶X射线衍射分析表明，呋喃环的变形角分别为3.69 °和16.00 °。这些变形角是1，4-二酮连接的低聚呋喃大环系列中最大的。虽然这两种大环化合物可能是杯[2]型大环化合物的最有前途的前体，但Paal-Knorr型吡咯或呋喃环的形成在用于杯[3]吡咯或杯[3]呋喃的标准条件下不进行。理论计算表明，在环状四酮上形成第二个芳环是一个非常上坡的过程，其活化能不能被标准的热反应所克服。
Recent progress in the synthesis of calix[3]pyrrole has proven that cyclic polyketones composed of 3,3-dialkylated pentane-2,4-diones as the repeating unit are promising precursors for strained calix-type macrocycles. Toward the synthesis of calix[2]pyrrole and calix[2]furan, which are the most strained congeners among the possible calix[]pyrroles and calix[]furans, we report the synthesis of a cyclic dimer of 3,3-dimethylpentane-2,4-dione and its furanophane derivative. These compounds were produced from a linear tetraketone precursor. Single crystal X-ray diffraction analysis revealed that the furan ring in the furanophane was highly strained with deformation anglesandof 3.69and 16.00, respectively. These deformation angles were the largest in the series of 1,4-diketone-linked oligofuran macrocycles. Although these two macrocyclic compounds are likely the most promising precursors for calix[2]-type macrocycles, Paal–Knorr-type pyrrole or furan ring formation did not proceed under standard conditions used for calix[3]pyrrole or calix[3]furan. Theoretical calculations indicated that the second aromatic ring formation on the cyclic tetraketone is a highly uphill process whose activation energy cannot be overcome by standard thermal reactions.