Development of Catalytic Asymmetric C-H Functionalizations with Chiral Cyclopentadienyl Iridium(III) Complexes

Cp*Ir(III) catalyzed C-H functionalization is a growing field, since it provides novel complementary reactivities, but enantioselective C-H functionalization reactions with this metal remain a niche. This thesis investigates CpXIr(III) catalyzed asymmetric, ortho-directed C-H functionalization reactions. While exploring an efficient enantioselective C-H amidation process, several chiral carboxylic acids were evaluated. A pronounced matched/ mismatched phenomenon between a chiral CpXIr(III) catalyst and (S)- and (R)-phthaloyl-tert leucine was found. This phenomenon was exploited to access highly enantioenriched P-chiral compounds. The corresponding phosphines are highly promising candidates as ligands for asymmetric catalysis. The enantioselective C(sp2)-H amidation of prochiral biaryl-phosphorus(V) compounds with various sulfonyl azides furnished the corresponding P-chiral products with up to 95% yield and up to 99:1 er. The cooperative system of CpXIr(III) and (S)-phthaloyl-tert leucine catalyzes a highly enantioselective C-H arylation reaction of phosphine oxides with ortho-quinone diazides. The catalytic reaction furnished the corresponding P-chiral phosphine oxides in up to 98% yield with 98.5:1.5 er. By using 1,2 diazonaphthol derivatives for the asymmetric C-H arylation reaction of phosphine oxides, a stable chiral axis was successfully implemented, giving access to P-chiral and axially chiral diastereomeric phosphorus(V) compounds with high selectivities and yields. Purely axially chiral phosphine oxides were also provided via an atropo-enantioselective C-H functionalization with up to 96:4 er and up to 95% yield. Additionally, chiral phosphorus(V) compounds were alkylated and reduced to their corresponding chiral phosphorus(III) compounds, without erosion of optical purity.

Cramer, Nicolai
Lausanne, EPFL

 Record created 2019-07-29, last modified 2019-07-29

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