Pulling Outward but Reacting Inward: Mechanically Induced Symmetry-Allowed Reactions of cis- and trans-Diester-Substituted Dichlorocyclopropanes
Pulling Outward but Reacting Inward: Mechanically Induced Symmetry-Allowed Reactions of cis- and trans-Diester-Substituted Dichlorocyclopropanes
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向外拉但向内反应：顺式和反式二酯取代的二氯环丙烷的机械诱导对称反应
DOI：
10.1055/a-1760-8817
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发表时间：
2022
期刊：
影响因子：
2
通讯作者：
Craig, Stephen L.
中科院分区：
文献类型：
--
作者：
Wang, Zi;Kouznetsova, Tatiana B.;Craig, Stephen L.
通过超声处理和单分子力谱（SMFS）研究证明了顺式和反式偕二氯环丙烷（gDCC）双酯的机械诱导顺式和反式异构体允许的对旋开环。与先前报道的烷基-tetered trans-gDCC的双酯禁止的对旋开环相反，我们表明，即使在超声和SMFS实验的高作用力（>2 nN）和短时间尺度（ms或更少）下，二酯-tetered trans-gDCC也主要经历双酯允许的对旋路径。从SMFS数据获得的定量力-速率数据与过渡态几何的计算模型一致，对于顺式-gDCC二酯和反式-gDCC二酯，分别推断活化长度为1.41 ± 0.02 μ m和1.08 ± 0.03 μ m。考虑到所施加的力的方向性最初可能出现与反应相关的反旋运动相反，在thetrans-gDCC中的强机械化学耦合是值得注意的。由酯连接产生的机械偶联的立体化学扰动增强了共价聚合物机械化学中可能的复杂性，并说明了通过明智的机械基团设计可获得的反应性结果的广度。
The mechanically induced symmetry-allowed disrotatory ring openings ofcis- andtrans-gem-dichlorocyclopropane (gDCC) diesters are demonstrated through sonication and single-molecule force spectroscopy (SMFS) studies. In contrast to the previously reported symmetry-forbidden conrotatory ring opening of alkyl-tetheredtrans-gDCC, we show that the diester-tetheredtrans-gDCC primarily undergoes a symmetry-allowed disrotatory pathway even at the high forces (>2 nN) and short-time scales (ms or less) of sonication and SMFS experiments. The quantitative force-rate data obtained from SMFS data is consistent with computational models of transition-state geometry for the symmetry-allowed process, and activation lengths of 1.41 ± 0.02 Å and 1.08 ± 0.03 Å are inferred for thecis-gDCC diester andtrans-gDCC diester, respectively. The strong mechanochemical coupling in thetrans-gDCC is notable, given that the directionality of the applied force may appear initially to oppose the disrotatory motion associated with the reaction. The stereochemical perturbations of mechanical coupling created by the ester attachments reinforce the complexity that is possible in covalent polymer mechanochemistry and illustrate the breadth of reactivity outcomes that are available through judicious mechanophore design.