1. Preparation of Complexes Bearing N‐Alkylated, Anionic or Protic CAACs Through Oxidative Addition of 2‐Halogenoindole Derivatives
- Author
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Constantin G. Daniliuc, F. Ekkehardt Hahn, Jonas Blumenberg, Alexander Hepp, and Sebastian Termühlen
- Subjects
Tetrafluoroborate ,oxidative addition ,Protonation ,Alkylation ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,chemistry.chemical_compound ,protic CAACs ,chloro indolium salts ,CAAC complexes ,Indole test ,010405 organic chemistry ,Ligand ,Communication ,General Medicine ,General Chemistry ,chloro indole ,Toluene ,Oxidative addition ,Communications ,0104 chemical sciences ,chemistry ,Yield (chemistry) ,CAAC and pCAAC Complexes - Abstract
CAAC precursors 2‐chloro‐3,3‐dimethylindole 1 and 2‐chloro‐1‐ethyl‐3,3‐dimethylindolium tetrafluoroborate 2BF4 have been prepared and oxidatively added to [M(PPh3)4] (M=Pd, Pt). Salt 2BF4 reacts with [Pd(PPh3)4] in toluene at 25 °C over 4 days to yield complex cis‐[3]BF4 featuring an N‐ethyl substituted CAAC, two cis‐arranged phosphines and a chloro ligand. Compound trans‐[3]BF4 was obtained from the same reaction at 80 °C over 1 day. Salt 2BF4 reacts with [Pt(PPh3)4] to give cis‐[4]BF4. The neutral indole derivative 1 adds oxidatively to [Pt(PPh3)4] to give trans‐[5] featuring a CAAC ligand with an unsubstituted ring‐nitrogen atom. This nitrogen atom has been protonated with py⋅HBF4 to give trans‐[6]BF4 bearing a protic CAAC ligand. The PdII complex trans‐[7]BF4 bearing a protic CAAC ligand was obtained in a one‐pot reaction from 1 and [Pd(PPh3)4] in the presence of py⋅HBF4., Cyclic (alkyl)(amino)carbene (CAAC) precursor salt 2BF4 reacts with [M(PPh3)4] (M=Pd, Pt) to give cis/trans‐[3]BF4 and cis‐[4]BF4, in which the CAAC ligand bears an unusual N‐alkyl substituent. trans‐[5] has a unique anionic CAAC ligand with an unsubstituted ring‐nitrogen atom which can be protonated to give trans‐[6]BF4 bearing a protic CAAC (pCAAC) ligand.
- Published
- 2020