Tandem hydroformylation/isomerization/hydrogenation of bio-derived 1-arylbutadienes for the regioselective synthesis of branched aldehydes

Abstract

The rhodium-catalyzed hydroformylation of 1-arylbutadienes derived from lignocellulosic bio-resources has been carried out in toluene and green solvents. In the presence of DPPE and XANTPHOS ligands, a regioselective Markovnikov Rh-H insertion takes place resulting in branched aldehydes in high selectivity, which contrasts with previous results obtained from aliphatic conjugated dienes. Depending on the nature of the diphosphine ligand, conjugated enals or saturated aldehydes are obtained in good to excellent selectivity. The later have a potential interest for fragrance industry, as they are homologous to commercial fragrance ingredients.

Transformations of bio‐sourced 4‐hydroxyphenylpropanoids based on olefin metathesis

“…The o-allylphenol (83) was thus reacted with benzyl hex-5enoate (84) in two steps in the presence of 1 and then 4 mol% of Ru13 in THF at 22°C to produce (86) in 63 % isolated yield with excellent (Z)-stereoselectivity (Scheme 21). [61] With the same strategy, chavicol (4) and methyl eugenol (5) were transformed into the corresponding allyl alcohol derivatives (87)- (89) in the presence of 1 and then 5 mol% of Ru14 at 22°C using (Z)-butene (85) as methylene capping agent and (Z)-2-methyl but-2-enol or its benzyl ether as coupling partner (Scheme 22).…”

“…The metathesis reaction was carried out in dichloromethane with 2 mol% of Ru4 or Ru7 and led to the allylic chlorides (116)-(120) in good yields with (E)selectivity (Scheme 33). [83,84] Two protocols were suitable for the elimination step. One involved the dehydrochorination in the presence of [RuCp*(MeCN) 3 ]PF 6 as catalyst and was performed in acetonitrile at room temperature, the other was based on the use of Pd(OAc) /PPh 3 to promote the same reaction at 90°C.…”

“…The bio-sourced dienes (121)-(123) have then been used to study their rhodium-catalyzed hydroformylation. [84]…”

“…Cross metathesis with dienes. Stereoretentive cross-metathesis of o-allylphenol(83) with the olefin(84). Stereoretentive cross metathesis with (Z)-trisubstituted allylic alcohol substrates.…”

Valorisation of mixtures of linear alkenes using cobalt-mediated isomerisation and hydroformylation chemistries

“…In terms of the ligand to be used, we hypothesised that cobalt catalysts incorporating the Xantphos ligand 17 (Xantphos = (9,9-dimethyl-9 H -xanthene-4,5-diyl)bis(diphenylphosphane); L ) could be appropriate given its wide bite angle 17 that could favour the preferential formation of C 1 -aldehydes. While rhodium-catalysed hydroformylations using Xantphos-type ligands 17,18 have been well studied, their use in cobalt-catalysed hydroformylation remains unexplored. We also hypothesised that the use of an excess of cobalt centres (as a tool to mediate CC bond isomerisation) with respect to the ligand could lead to the discovery of selective catalysts for the addition of a CHO group to the C 1 carbon of the alkene skeleton (Scheme 1).…”