Transition-Metal-Free ipso-Arylative Condensation

Abstract

The development of economical synthetic methods remains an important step toward the widespread use of conjugated polymers. Most well-established methods require either prefunctionalization with organometallic reagents or the use of expensive transition-metal catalysts. We have shown that 2-hydroxyalkyl- and 2-hydroxyaryl-substituted thiazole N-oxides can proceed through an ipso-arylative condensation that yields bithiazole-containing conjugated small molecules and polymers. The use of 2-hydroxyaryl substituents enables access to a wide scope of thiazole N-oxide substrates and presents an economical route to the synthesis of bithiazole-based conjugated polymers with varying physical and electronic properties.

Regioselective Direct C−H Bond (Hetero)arylation of Thiazoles Enabled by a Novel Iminopyridine-Based α‐Diimine Nickel(II) Complex Evaluated by DFT Studies.

“…C NMR (500 MHz, CDCl3, 300 K), δ (ppm): 152.73, 139.84, 133.98, 133.56, 129.40, 128.97, 128.53, 128.27, 127.35, 127.05, 126.40, 125.22. 1 H and13 C NMR spectra are consistent with previous reports 74. 4Purified via silica gel column chromatography using n-hexane and ethyl acetate as eluents in a ratio of 10:1 (v/v).…”

Regioselective Direct C–H Bond Heteroarylation of Thiazoles Enabled by an Iminopyridine-Based α-Diimine Nickel(II) Complex Evaluated by DFT Studies

“…13 C{ 1 H} NMR (500 MHz, CDCl 3 ): δ (ppm) 152.7, 139.8, 134.0, 133.6, 129.4, 129.0, 128.5, 128.3, 127.4, 127.1, 126.4, 125.2. 1 H and13 C NMR spectra are consistent with the previous report 52. Purified via silica gel column chromatography using n-hexane and ethyl acetate as eluents in a ratio of 10:1 (v/v).…”

N-Oxide S–O chalcogen bonding in conjugated materials

“… 42 Bithiazole N -oxide 1b was achieved through our previously reported ipso -arylative condensation, while further oxidation of this product with m -CPBA yielded 1c . 41 The UV-vis absorption spectra of bithiazoles 1a , 1b and 1c were recorded in CHCl 3 to determine the optical band gaps of the small molecules ( Fig. 2 ).…”

“…Recently, we reported novel approaches towards the synthesis of bithiazole-containing conjugated polymers through both transition-metal-free dehydrative polymerization, and ipso-arylative polymerization, of thiazole N-oxides. 40,41 While these types of transition-metal-free approaches to the synthesis of polyheterocyclic conjugated polymers are rare, bithiazole N-oxide-containing polymers produced in this manner represent a new class of unexplored polymers with the potential for unique physical and electronic properties. Herein, we describe the investigation of conjugated small molecules and polymers possessing bithiazole N-oxide and N,N 0 -dioxide moieties, and the effect that the N-oxide functionality has on both the electronic and physical properties of the materials (Fig.…”