A Sequential Pd/Norbornene-Catalyzed Process Generateso-Biaryl Carbaldehydes or Ketones via a Redox Reaction or 6H-Dibenzopyrans by C–O Ring Closure

Abstract

o-Biaryl carbaldeydes and ketones are obtained through the one-pot reaction of o-aryl iodides with o-bromobenzyl alcohols under the catalytic action of Pd and norbornene, in the presence of a base. The same reaction can also give dibenzopyrans by Pd and norbornene catalysis with a different termination, leading to C-O ring closure. In both cases the process first leads to a five-membered palladacycle, which controls C-C coupling, then to a seven-membered oxapalladacycle, which gives aldehydes and ketones or dibenzopyrans.

The vinylogous Catellani reaction: a combined computational and experimental study

“…Catellani and co-workers reported that the reaction of iodobenzenes with o -bromobenzylic alcohols bearing no benzylic hydrogen proceeded in the presence of a palladium catalyst and NBE to produce dibenzopyrans. 12 According to their procedure, 2a and 3a were treated with 5 mol% Pd(OAc) 2 , 1 equiv. of NBE, and 2.5 equiv.…”

“…These results suggest that tertiary benzyl alcohols are essential for high-yield formation of the chromeno-2-quinolones because primary and secondary benzyl alcohols undergo oxidation under the reaction conditions, as reported by Catellani and coworkers. 12 …”

From catechol‐tocopherol to catechol‐hydroquinone polyphenolic antioxidant hybrids

“…Thus, we decided to follow a different approach for the construction of biphenyl units based on a Pd/norbornene dual catalysis process [11]. As starting materials for this procedure, we prepared bromo derivative 2 , obtained from commercially available 6‐bromo‐veratraldehyde by addition of MeMgBr, oxidation to the corresponding methyl ketone and a further addition of MeMgBr, and iodo derivatives 3 and 4 as the result of the iodination with I 2 /HIO 3 of 2,3‐dimethyl‐ and 2,3,5‐trimethyl anisole, respectively (Scheme ).…”

“…We tried then to apply the mentioned procedure,[11] reacting derivative 2 with 3 , or 4 , in the presence of catalytic amounts of Pd(OAc) 2 , 1.0 equiv of norbornene and dry K 2 CO 3 in dry DMF at 105°C. Under this condition, after 24 hours, we were able indeed to isolate derivative 5 ( R =H) in 64% yield.…”

Cis,exo-1,2,3,4,4a,13b-hexahydro-1,4-methano-5-isopropoxy-9H-tribenzo[b,f]azepine

“…Over the years, this palladium/norbornene-catalyzed C-H activation and functionalization reaction has been proven to be a powerful tool for the construction of complex molecules in a one-pot fashion [7,8]. In this context, we have successfully applied this methodology to the synthesis of many compounds, including natural product derivatives [9][10][11][12][13][14][15][16][17][18][19][20]. Notably, in 2011, we enriched the versatility of the Catellani reaction by the synthesis of dibenzo[b,f ]azepines [21].…”