Aryl and Heteroaryl N1‐Tetrazoles through Ligand‐Free Suzuki‐Reaction under Aerobic, Aqueous Conditions

Abstract

Substituted 1‐biaryl‐1H‐tetrazoles are classically obtained from the corresponding 1‐aminobiaryls, limiting the selection of substrates. The development and substrate scope of a green, ligand‐free Suzuki protocol in aqueous media under ambient atmosphere, leading to 1‐biaryl‐ and heteroaryl‐substituted 1H‐tetrazoles in very good to excellent yields is presented. The combination of PdCl2/NEt3/H2O/EtOH was found to combine high yields and high purity for all substrates investigated. Comparative experiments investigating the reaction rate showed that the tetrazole does not act as a ligand for the palladium catalyst.

Halogenated Alkyltetrazoles for the Rational Design of FeII Spin‐Crossover Materials: Fine‐Tuning of the Ligand Size

“…Although the final halogenation step under microwave conditions was successful, only poor yields of around 12 % could be obtained. This was attributed to the presence of the tetrazole, probably due to its Lewis basic properties, which has previously proven problematic in ligand functionalization …”

“…[22] Therefore, an alternative approach based on the Frankes ynthesis was selected, [16] which avoided any furtherf unctionalization. Although the final halogenation step under microwave conditions wass uccessful, only poor yields of around1 2% could be obtained.…”

Unsaturated Aryl and Heteroaryl N1-Tetrazoles from 1-Allyl-1H-tetrazole

“…Recently, it has been demonstrated that alkylation under microwave conditions, 17 or Suzuki coupling 18 21 and finally also on their use as ligand for various coupling reactions. 22 In the present study unsaturated aryl-and heteroaryl N1-tetrazoles were targeted by using a Heck cross-coupling protocol with 1-allyl-1H-tetrazole as central structural motif.…”

“…The interaction of the 1-allyl-1Htetrazole with Pd 2+ , thus being involved in the catalytic cycle, was excluded earlier, demonstrating a non-detectable affinity of the tetrazole to the catalytic Pd species. 18 To optimize the catalyst loading, the conditions identified were used in the model reaction (Scheme 2), varying the Pd concentration between 0.63 and 5 mol% ( Figure S1).…”

Bifunctional Fe(ii) spin crossover-complexes based on ω-(1H-tetrazol-1-yl) carboxylic acids

“…In this case, Fe(II) switches between a paramagnetic HS state with S=2 and a diamagnetic LS state with S=0. In previous work, we have emphasized fine-tuning of the ligands' geometry and flexibility, shaping cooperativity and transition temperature on a molecular scale, 25,26 as well as post functionalization of the ligand backbone. 27 Therefore, in this work, a carboxylic acid moiety has been introduced to the ligand system, allowing for the investigation of the SCO in [Fe(ω-(1Htetrazol-1-yl) carboxylic acid)6] 2+ -cations.…”