Pd-catalyzed Dithiolene–Aryl Cross-coupling Reaction of Aromatic Cyclopentadienylcobalt Dithiolene Complex

Abstract

[CpCo(dithiolene)] complex with a boronate group, which is formulated as [CpCo{S2C2(Ph)(Bpin)}] (1, Bpin = 4,4,5,5-tetramethyl-1,3,2-dioxaboronate), was prepared from the one-pot reaction of [CpCo(CO)2], elemental sulfur, and boronated alkyne. 1 underwent Pd-catalyzed Suzuki–Miyaura cross-coupling reactions with 3-bromopyridine or 9-bromoanthracene.

Pd-catalyzed boronations and cross-coupling reactions of aromatic cobaltadithiolene complexes with aryl halides

“…Cross-coupling reaction of boronated dithiolene ring with aryl halides An early communication paper described the cross-coupling reaction of 1 with 3-bromopyridine or 9-bromoanthracene in the presence of [Pd(PPh 3 ) 4 ] to form [CpCo(S 2 C 2 (Ph)(3-Py))] (2) or [CpCo(S 2 C 2 (Ph)(9-Anth))] (3), respectively [15]. The Pd-catalyzed reactions of 1 with aryl halides are summarized in Table 1.…”

“…These results suggest that use of a strong base undergoes deprotection of the Bpin group from 1 and can not ensure effective formation of the cross-coupling product. In fact, the treatment of 1 with Na 2 CO 3 in THF gave the hydrogenated product 6 in 30% yield [15]. In this work, the cross-coupling reaction of 1 with 1-iodonaphthalene or 2-bromothiophene in the presence of triethylamine gave [CpCo(S 2 C 2 (Ph)(1-Np))] (4, 4% yield) or [CpCo(S 2 C 2 (Ph)(2-Th))] (5, 2% yield) as shown in Scheme 1 and Table 1 (Entries 5 and 6).…”

“…According to an early communication paper by our research group, the cobaltadithiolene complex having a boronated ester group, which is formulated as [CpCo(S 2 C 2 (Ph)(Bpin))] (1, Bpin ¼ 4,4,5,5-tetramethyl-1,3,2-dioxaboronate), shows dithiolene-aryl cross-coupling reactions in the presence of Pd catalyst (Scheme 1) [15]. This has been the first case of SuzukieMiyaura cross-coupling reaction [16] to a pseudo aromatic metallacycle.…”

Sulfur-centered and nitrogen-centered radical substitution reactions of aromatic CpCo(dithiolene) complex with 2,2′-Dibenzothiazolyl disulfide

“…On the basis of aromaticity of the metallacycle, the Friedel-Crafts acylation occurs on the dithiolene carbon of [CpCo(S 2 C 2 (R)(H))] complex in the presence of Lewis acid [9]. Quite recently, we reported the Suzuki-Miyaura cross-coupling reaction between the boronated [CpCo(S 2 C 2 (Ph)(Bpin))] (Bpin ¼ 4,4,5,3, complex and aryl halides in the presence of Pd catalyst [10].…”

Two near-UV and visible chromophores of CpCo(Dithiolene) complexes with pyridinium-dicyanomethylide group

“…In fact, we developed some electrophilic substitutions, radical substitutions [7] and Suzuki-Miyaura cross-coupling reactions [8] by the aromaticity of metalladithiolene ring. On the other hand, addition reactions due to the unsaturation have been much more developed [9e16].…”