Direct and Regioselective Introduction of Acetals into Imidazoles at the 2‐Position by an Iridium‐Catalyzed Reaction with Formates in the Presence of Hydrosilanes. Issue 12 (31st March 2017)

• Record Type: Journal Article
• Authors: Fukumoto, Yoshiya; Iyori, Yasuaki; Chatani, Naoto
• Is Part Of: European journal of organic chemistry. Issue 12(2017)
• Page Start: 1662
• Page End: 1665
• Publication Date: 2017-03-31
• Subjects: C–H activation -- Hydrolysis -- Iridium -- Nitrogen heterocycles -- Silanes; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201700125
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : The iridium‐catalyzed reaction of imidazoles with formates in the presence of hydrosilanes as coreactants led to the production of 2‐[(alkoxy)(siloxy)methyl]imidazoles. Dimethyl acetylenedicarboxylate was the additive of choice for the reaction in terms of reaction efficiency. No reaction was observed in the absence of the hydrosilanes. Whereas substituents at the 1‐ and 5‐positions on the imidazole ring did not affect the reaction, substituents at the 4‐position greatly retarded the reaction. The regioselective reaction of 1‐methyl‐1, 2, 4‐triazole occurred at the carbon atom between the sp 3 and sp 2 nitrogen atoms of the ring but not between two sp 2 nitrogen atoms. The products were converted into imidazole 2‐carbaldehydes by hydrolysis under acidic conditions. Abstract : The Ir‐catalyzed reaction of imidazoles with formates in the presence of hydrosilanes as coreactants produces 2‐[(alkoxy)(siloxy)methyl]imidazoles. Dimethyl acetylenedicarboxylate is the only effective additive, and the hydrosilanes must be added for the reaction to proceed. The product acetals undergo hydrolysis under acidic conditions to yield the corresponding imidazole 2‐carboxaldehydes.