Ring-contracted porphyrin analogues, such as subporphyrins and calix[3]pyrroles, have recently attracted considerable attention not only as challenging synthetic targets but also as functional macrocyclic compounds. Although canonical porphyrins and calix[4]pyrrole are selectively generated via acid-catalyzed condensation reactions of pyrrole monomers, their tripyrrolic analogues are always missing under similar conditions. Recent progress in synthesis has shown that strain-controlled approaches using boron(III)-templating, core-modification, or ring tightening provide access to various contracted porphyrins. The tripyrrolic macrocycles are a new class of functional macrocycles exhibiting unique ring-contraction effects, including strong boron chelation and strain-induced ring expansion. This Perspective reviews recent advances in synthetic strategies and the novel ring-contraction effects of subporphyrins, triphyrins(2.1.1), calix[3]pyrroles, and their analogous.

中文翻译：

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收缩卟啉和杯吡咯：合成挑战和环收缩效应

缩环卟啉类似物，例如亚卟啉和杯[3]吡咯，最近不仅作为具有挑战性的合成目标，而且作为功能性大环化合物引起了相当大的关注。尽管典型的卟啉和杯[4]吡咯是通过吡咯单体的酸催化缩合反应选择性生成的，但在相似的条件下它们的三吡咯类似物总是缺失。合成方面的最新进展表明，使用硼 ( III ) 模板、核心修饰或环紧缩的应变控制方法可提供各种收缩卟啉。三吡咯大环化合物是一类新型功能性大环化合物，表现出独特的环收缩效应，包括强硼螯合和应变诱导的环扩张。本综述回顾了亚卟啉、三卟啉(2.1.1)、杯[3]吡咯及其类似物的合成策略和新型环收缩效应的最新进展。