Structure- and Functionality-Based Molecular Design of Azoles and Thiophenes

Abstract

Heteroaromatic structures are widely found in a variety of organic molecules such as π-extended oligomers/polymers, pharmaceutical drugs, agrochemicals, etc. Considerable efforts have been made for the wide use of heteroaromatic compounds. It is therefore of great interest to develop efficient and practical synthetic methodology in organic chemistry. In this account, the focus is on the molecular design of five-membered heteroaromatic compounds such as azoles and thiophenes covering transition metal-catalyzed carbon–carbon and carbon–heteroatom bond formation at the C–H bond, polymerization reactions employing coupling reactions, and a new class of structural design of heterobiaryls showing molecular asymmetry.

Generation of Sodium‐Thiophene Species with Metal Amide‐Free Approach Toward Polythiophene Synthesis by Cross‐Coupling Polymerization

“…In particular, our recent concern has been centered to the synthesis of polythiophene, which proceeds through the cross-coupling polymerization catalyzed by nickel(II). [4][5][6][7][8][9][10] We have recently reported that the use of thiopheneÀ sodium species 1 as an organometallic monomer for the polythiophene synthesis, [11] which involves deprotonative metalation of thiophene 2 with sodium amide composed of the metalated 2,2,6,6-tetramethylpiperidine (TMPNa: 3). [12] The major drawback of such a process is the in-situ formation of the corresponding secondary amine 4 in the polymerization mixture [13,14] as well as the preparation of sodium amide with metallic sodium species through several steps.…”

“…Accordingly, it is intriguing to develop a more simplified and straightforward protocol for the formation of metallothiophene monomer 1 (Z=Na) (Scheme 1). Herein, we describe that deprotonative metalation of 2-chloro-3-hexylthiophene (2 a) proceeds with phenyl sodium (5) in hexane as an aprotic solvent in the presence of a small amount of an additive and the thus formed organometallic thiophene is successfully employed for the polythiophene synthesis.…”

Synthesis and Racemization Studies of Winding Vine‐Shaped Biphenyl Derivatives

“…[1] As shown in Scheme 1, we have previously shown that several heterobiaryls bearing substituents with terminal alkenes undergo ring-closing metathesis [2] leading to the cyclized product 1, where the obtained carboncarbon double bond showed E-stereochemistry. [3,4] We named such a compound of the (hetero)biaryl structure, each of which aromatic ring was connected by a certain number of alkylene chain, as winding vine-shaped molecule. [5] It was also revealed that the obtained product exhibited molecular asymmetry, in which axial, helical, and planar chiralities were involved in the molecule and their inversion of the chirality took place in a synchronized manner.…”

Introductory Chapter: Azoles, Their Importance, and Applications

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versatile and useful compounds with potential applications in various areas such as materials, energetics, catalysis, etc. The intensive research work in the area of azoles, covering synthesis, characterization, and computational studies of their various novel derivatives is continuously ongoing [44,[47][48][49][50][51][52]. Thus, the area of azoles and their derivatives, their physico-chemical properties, and applications is of continuous high interest, and therefore this book will be a valuable addition to the knowledge which has been accumulated so far in this field.

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