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SET/HAT flips benzylamine C–H arylation site
PhC(O)SH plus Ir(ppy)3 switches photoredox arylation from N-methyl C–H to the benzylic position, giving 1,1-diarylmethylamines in hours.
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What transformation is targeted?
Benzylic Csp3–H arylation of benzylamines to 1,1-diarylmethylamines.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
SET-only regioselectivity on 1a?
Major product from the N-methyl (1°) α-amino radical, not benzylic.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
How long does SET-only take?
12 h for completion, 95% mass balance.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
Which HAT precatalyst inverts selectivity?
Thiobenzoic acid / PhC(O)SK.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
Why oxidize the thiolate first?
PhC(O)SK Epox = +0.80 V vs SCE, easier than the amine, blocking aminium formation.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
BDE driving force for HAT?
PhC(O)S–H 87.4 vs benzylic C–H 84.9 kcal mol–1.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
Minimum catalyst loadings that still work?
0.5 mol% Ir(ppy)3 and 1 mol% PhC(O)SH, 90% of 2a.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
Is excess amine required?
No; stoichiometric 1a still gives good yield.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
How fast is the HAT protocol?
Complete within 1–2 h versus 12 h without thiol.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
Scope yield range?
56–98% for various 1,1-diarylmethylamines.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified
Can it functionalize pharmaceuticals?
Yes; late-stage N-benzyl arylation of drugs with reactive functional groups.
Source: Regio- and chemoselective Csp<sup>3</sup>-H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis · DOI · quote verified