Abstract

The “precursor approach” has proved particularly valuable for the preparation of insoluble and unstable π-conjugated polycyclic compounds (π-CPCs), which cannot be synthesized via in-solution organic chemistry, for their improved processing, as well as for their electronic investigation both at the material and single-molecule scales. This method relies on the synthesis and processing of soluble and stable direct precursors of the target π-CPCs, followed by their final conversion in situ, triggered by thermal activation, photoirradiation or redox control. Beside well-established reactions involving the elimination of carbon-based small molecules, i.e., retro-Diels–Alder and decarbonylation processes, the late-stage extrusion of chalcogen fragments has emerged as a highly promising synthetic tool to access a wider variety of π-conjugated polycyclic structures and thus to expand the potentialities of the “precursor approach” for further improvements of molecular materials’ performances. This review gives an overview of synthetic strategies towards π-CPCs involving the ultimate elimination of chalcogen fragments upon thermal activation, photoirradiation and electron exchange.

Beilstein J. Org. Chem. 2024, 20, 287–305. doi:10.3762/bjoc.20.30

摘要

事实证明，“前驱体方法”对于制备不溶性且不稳定的π-共轭多环化合物（π-CPC）（无法通过溶液内有机化学合成）、改进加工以及电子研究特别有价值在材料和单分子尺度上。该方法依赖于目标 π-CPC 的可溶且稳定的直接前体的合成和加工，然后通过热活化、光照射或氧化还原控制触发它们的最终原位转化。除了涉及消除碳基小分子的成熟反应（即逆狄尔斯-阿尔德反应和脱羰过程）之外，硫属元素片段的后期挤出已成为一种非常有前途的合成工具，可用于获得更广泛的 π-共轭多环结构，从而扩大了“前驱体方法”进一步改善分子材料性能的潜力。本综述概述了 π-CPC 的合成策略，涉及通过热活化、光照射和电子交换最终消除硫族元素碎片。

贝尔斯坦 J. 组织。化学。 2024, 20, 287–305。 doi:10.3762/bjoc.20.30