Iridium Pyridine‐Thienyl ( Ir‐PYT ) Catalyst for C  H Borylation

Abstract

[2624407-43-6] C18H20IrNS (MW 474.64) InChI = 1S/C10H8NS.C8H12.Ir/c1-8-2-3-10(11-6-8)9-4-5-12-7-9;1-2-4-6-8-7-5-3-1;/h2-6H,1H3;1-2,7-8H,3-6H2;/b;2-1-,8-7-; InChIKey = XGABZFMRMMJLTA-GHDUESPLSA-N (reagent used as a catalyst in directed C(sp2)H and C(sp3)H borylation and selective heterocyclic molecule borylation) Alternative Name(s): Ir-PYT first-generation catalyst, Chattopadhyay's first-generation Ir catalyst (CB1). Physical Data: melting point above 200 °C. Solubility: soluble in CHCl3, CH2Cl2, PhH, MeOH, and THF; limited solubility in hexane. Form Supplied in: black solid. Commercially not available. Analysis of Reagent Purity: (NMR and HRMS). 1H NMR (400 MHz, CDCl3): δ 7.65 (s, 1H), 7.50 (d, J = 8.0 Hz, 1H), 7.28 (d, J = 8.0 Hz, 1H), 7.25 (d, J = 5.2 Hz, 1H), 7.19 (d, J = 4.8 Hz, 1H), 4.35 (br s, 2H), 4.20 (br s, 2H), 2.34–2.37 (m, 4H), 2.25 (s, 3H), 1.87–1.91 (m, 4H). HRMS (ESI) m/z calcd for C18H21IrNS [M + H]+ 476.1018, found 476.1009. X-Ray data: CCDC No. 2002760. Preparative Methods: the iridium pyridine-thienyl (Ir-PYT) catalyst was prepared1 through a three-step process: Miyaura borylation of the commercially available 3-bromothiophene followed by a Suzuki–Miyaura cross-coupling with 2-bromo-5-methyl pyridine and subsequent treatment with [Ir(cod)OMe]2 to yield the catalyst (Scheme 1). Caution: The last step is air sensitive, and the compound isolated under inert conditions or in glove box. Purification: after the reaction of the last step, all the volatilities were removed under argon atmosphere and dried for 20 min under vacuum. After that, the catalyst was obtained as a black powder. Crystallization was done in THF/hexane solvent. Handling, Storage, and Precautions: the iridium complex is air sensitive and stable in inert atmosphere at room temperature. No information is currently available in terms of the reagent's effect on health.