Synthesis of Shape‐Persistent Macrocycles by a One‐Pot Suzuki–Miyaura Cross‐Coupling Reaction

Abstract

Shape-persistent macrocycles have attracted considerable interest as molecular components in the fields of supramolecular chemistry and materials science due to their unique molecular structures and properties. These rigid molecular rings with a nanoscale sized hole in the center may be tailored with specific chemical constitutions, geometrical shapes, peripheral functional groups, and so on. Recent advances in the preparation, supramolecular self-assembling, and practical applications of shape-persistent macrocycles have verified this class of molecules as promising building blocks for supramolecular chemistry and nanodevice fabrication. Intense efforts have been devoted to the synthesis of shape-persistent macrocycles, and they have been well summarized in several excellent reviews. The most successful methods used in the synthesis of shape-persistent macrocycles include the following approaches: 1) intramolecular ring closure of a,w-difunctionalized oligomer strategy and the one-pot intermolecular coupling and intramolecular cyclization method; 2) the template strategy; 3) thermodynamically controlled synthetic strategies. Based on these elegant synthetic strategies, a large number of shape-persistent macrocycles with well-defined shapes and sizes have been prepared and reported. Recently, Sherburn and Sinclair found that Suzuki– Miyaura coupling of diiodoaryls and arylboronic acid in a feed ratio of 10:1 afforded the product of double coupling in good yields. Hu and Dong demonstrated that the use of [Pd2ACHTUNGTRENNUNG(dba)3] and tBu3P as the catalyst precursor for Suzuki– Miyaura cross-coupling of dibromobenzenes with arylboronic acid (1 equiv) afforded exclusively diaryl-substituted benzenes. Scherf et al. reported the cross-coupling of 2,7-dibromofluorene with arylboronic acid (1 equiv) formed preferentially the diaryl-substituted fluorenes. Yokozawa et al. reported chain-growth Suzuki–Miyaura polymerization of an AB-type monomer, bromoarylboronic acid, using [PdBr{P ACHTUNGTRENNUNG(tBu)3}(Ph)] as an arylpalladium halide catalyst. Kiriy et al. have successfully grafted polyfluorene onto a functionalized surface by catalyst-transfer chain-growth Suzuki–Miyaura polycondensation of 7-bromo-9,9-bis(2ethyl-hexyl)-9H-fluoren-2-ylboric using [Pd ACHTUNGTRENNUNG(tBu3P)2] as the catalyst precursor. Very recently, Yokozawa et al. have demonstrated that catalyst-transfer Suzuki–Miyaura polycondensation can be used to prepare even diblock conjugated polymers with a narrow molecular weight distribution. We have recently demonstrated that the catalyst-transfer Suzuki–Miyaura cross-coupling (CTSMCC) reaction can be used to prepare hyperbranched polymers with a branching degree of 100%. We think the unique catalyst-transfer behavior can be used to prepare shape-persistent macrocycles. Herein, we report the application of the CTSMCC reaction in the preparation of shape-persistent macrocycles. To the best of our knowledge, this is the first example of the synthesis of macrocycles by the CTSMCC reaction. Four macrocycles were selected as targeted macrocycles to verify our idea. Due to the competition of linear polymerization, a onepot reaction usually affords macrocycles in very low yield. Therefore, the synthesis of shape-persistent macrocycles normally requires pseudo high dilution. The reactants are usually added to the reaction vessel by a syringe pump over [a] W. Huang, M. Wang, C. Du, Dr. Y. Chen, L. Su, C. Zhang, Prof. Dr. Z. Bo Institute of Chemistry CAS Beijing 100190 (P.R. China) Fax: (+86)10-82618587 E-mail : zsbo@iccas.ac.cn [b] Dr. R. Qin, Prof. Dr. Z. Liu, C. Li, Prof. Dr. Z. Bo Institute of Polymer Chemistry and Physics College of Chemistry, Beijing Normal University Beijing 100875 (P.R. China) Fax: (+86)10-62206891 E-mail : zsbo@bnu.edu.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201002574.