Synthetic Strategy for Multisubstituted Fused Furan Compounds Using Main-Group Metal Reagents

Abstract

In this account, we summarize our recent studies on the synthesis of multisubstituted furan compounds. The synthetic strategy relies on the electrophilic cyclization of o-hydroxy(alkynyl)arenes by using main-group metal reagents. For example, zinc salts have been found to mediate the cyclization of oalkynylphenols to form thermally stable yet chemically reactive β-zincio intermediates ('synthetic modules') that serve as platforms for the syntheses of a series of analogues having the same core structural motif (the 'molecular library'). This modular approach is applicable to the synthesis of new benzofurans and benzodifurans and their homologues, and allows us to study the photophysical and semiconducting properties of these products systematically. We have similarly developed a synthesis of benzotrifurans by a cesium hydroxide-mediated tandem S N Ar/triple-cyclization reaction, as well as a synthesis of trisubstituted furans by indium-catalyzed cycloisomerization of α-propargyl β-keto esters.

Extended benzodifuran–thiophene systems connected with azomethine junctions: synthesis and electronic properties

“…4 Benzofuran and benzodifuran moieties have emerged as efficient building blocks for the development of semiconductor materials for organic electronics. 5 Thus polymers or small molecules based on the benzo[1,2-b:4,5-b 0 ]difuran units (BDF) variously substituted on the benzenic core and/or the furan units (Scheme 1) have been used as active materials in OLEDs and OPCs. [5][6][7][8][9][10][11] On the other hand, the donor-acceptor (D/A) approach with electron-donating (D) and electron acceptor (A) blocks inserted in the conjugated backbone is currently one of the most widely investigated materials for the development of electronic plastics.…”

“…5 Thus polymers or small molecules based on the benzo[1,2-b:4,5-b 0 ]difuran units (BDF) variously substituted on the benzenic core and/or the furan units (Scheme 1) have been used as active materials in OLEDs and OPCs. [5][6][7][8][9][10][11] On the other hand, the donor-acceptor (D/A) approach with electron-donating (D) and electron acceptor (A) blocks inserted in the conjugated backbone is currently one of the most widely investigated materials for the development of electronic plastics. [12][13][14] Recently many donor-acceptor copolymers containing BDF building blocks were used as donor materials in OPC and power conversion efficiencies above 6% were achieved.…”

Recent Progress in Synthesis of Polysubstituted Furans

“…图式 9 2-硝基苯并呋喃的合成 Scheme 9 Synthesis of 2-nitroarenofurans Tsuji 和 Nakamura 等 [32] 以邻炔基酚为原料, 通过 BuLi-ZnCl 2 促进的分子内环化反应得到苯并呋喃-β-氯 化锌中间体. 该中间体质子化后直接得到三取代的呋 喃, 若在低温下接受亲电试剂进攻, 则可以转化为四取 代的呋喃(Scheme 10).…”

Synthesis, structure, and catalytic performance of solvent induced zinc clusters in furan synthesis by cycloisomerization reaction

“…Zinc halides (like ZnCl 2 , ZnBr 2 , and ZnI 2 ) have been investigated in detail, 26 and there are also some reports about using other zinc salts. 27 The results of these studies indicated that zinc clusters, like Zn 4 O(CF 3 COO) 6 , are more active and selective catalysts than other simple salts. 28 Nevertheless, there are seldom reports about the use of zinc clusters in the synthesis of furan derivatives via cycloisomerization reactions.…”