2009-59-8Relevant articles and documents
Rhodium versus iridium catalysts in the controlled tandem hydroformylation-isomerization of functionalized unsaturated fatty substrates
Ternel, Jrmy,Couturier, Jean-Luc,Dubois, Jean-Luc,Carpentier, Jean-Franois
, p. 513 - 520 (2015/03/04)
The hydroformylation of 10-undecenitrile (1) and related unsaturated fatty substrates (H2C=CH(CH2)7CH2R; R=CO2Me, CH2Br, CHO) has been studied with rhodium, iridium, ruthenium, and palladium biphephos catalysts. The reactions proceeded effectively with all four systems, with high selectivities for the linear aldehyde (ratio of linear/branched aldehydes=99:1). The biphephos-bis[chloro(cyclooctadiene)iridium] system showed a non-optimized hydroformylation turnover frequency (TOFHF) of 770h-1 that was only approximately 5times lower than that of the rhodium-based system (TOFHF=3320h-1); the palladium and ruthenium biphephos systems were less active (TOFHF=210 and 310h-1, respectively). Upon recycling, remarkable productivities were achieved in both cases (TON≈58-000mol(1/1-int)-mol(Ir)-1 and 250-000mol(1/1-int)-mol(Rh)-1, in which int=internal olefin). Competitive isomerization of terminal to internal olefins occurred with these catalysts. Iridium biphephos systems allowed slightly better control of the distribution of the internal isomers than the rhodium biphephos catalyst, with higher ratios of 9-/8-undecenitrile (1-int). Place your bets now: Iridium-biphephos catalysts are highly effective in the controlled tandem isomerization-hydroformylation of 10-undecenitrile and related functionalized unsaturated fatty substrates.
Direct terminal alkylamino-functionalization via multistep biocatalysis in one recombinant whole-cell catalyst
Schrewe, Manfred,Ladkau, Nadine,Buehler, Bruno,Schmid, Andreas
supporting information, p. 1693 - 1697 (2013/07/19)
Direct and regiospecific amino-functionalization of non-activated carbon could be achieved using one recombinant microbial catalyst. The presented proof of concept shows that heterologous pathway engineering allowed the construction of a whole-cell biocatalyst catalyzing the terminal amino-functionalization of fatty acid methyl esters (e.g., dodecanoic acid methyl ester) and alkanes (e.g., octane). By coupling oxygenase and transaminase catalysis in vivo, both substrates are converted with absolute regiospecificity to the terminal amine via two sequential oxidation reactions followed by an amination step. Such demanding chemical three-step reactions achieved with a single catalyst demonstrate the tremendous potential of whole-cell biocatalysts for the production of industrially relevant building blocks. Copyright
