Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic α,β-unsaturated carbonyl compounds

Abstract

Summary N-Methyl-N-((trimethylsilyl)methyl)aniline was employed as reagent in visible-light-induced, iridium-catalyzed addition reactions to cyclic α,β-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH) or 1.0 mol % (in CH2Cl2) [Ir(ppy)2(dtbbpy)]BF4 as the catalyst. Two major reaction products were obtained in combined yields of 30–67%. One product resulted from aminomethyl radical addition, the other product was a tricyclic compound, which is likely formed by attack of the intermediately formed α-carbonyl radical at the phenyl ring. For five-membered α,β-unsaturated lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed.

Synthetic Utilization of α-Aminoalkyl Radicals and Related Species in Visible Light Photoredox Catalysis

“…Subsequent oxidation and deprotonation give the corresponding 1,2,3,4-tetrahydroquinoline derivatives. Similar reactions under modified reaction conditions have been reported by several groups. ,− …”

Enantioselective Visible‐Light‐Induced Radical‐Addition Reactions to 3‐Alkylidene Indolin‐2‐ones

“…The low solubility of the commonly used ruthenium catalyst [Ru(bpy) 3 Cl 2 ] ( 2 ; bpy=2,2′‐bipyridine) in this solvent, let us look for alternative catalysts to be tested in possible radical‐addition reactions. Based on earlier work, the iridium complex [Ir(ppy) 2 (dtbbpy)]BF 4 ( 3 ; ppy=phenylpyridyl, dtbbpy=4,4′‐di‐ tert ‐butyl‐2,2′‐bipyridine) seemed to be a good choice, and it was studied whether addition reactions to Michael acceptors could be performed. We now disclose details of our studies, which revealed that 3‐alkylidene indolin‐2‐ones are readily attacked by a variety of radicals generated from α‐trimethylsilyl (TMS) methyl‐substituted amines, and that moderate to good enantioselectivity values can be achieved in this transformation.…”

Aminomethylations of electron-deficient compounds—bringing iron photoredox catalysis into play

“… 6 Upon single electron transfer (SET) induced oxidation of an alkylamine, the resulting amine radical cation is known to undergo further reactions, with some of the possible pathways highlighted in Scheme 1a . 7 Commonly, α-aminoalkyl radicals are accessed through deprotonation of the α-C-atom following amine oxidation via SET. Alternatively, they can be afforded through homolytic cleavage of the α-C–H bond by a hydrogen atom transfer catalyst.…”