Heavy-Metal-Free Fischer-Tropsch Type Reaction: Sequential Homologation of Alkylborane Using a Combination of CO and Hydrides as Methylene Source.

Carbon homologation reactions occur within the well-known Fischer-Tropsch process, usually mediated by transition metal catalysts at high temperature. Here we report the low-temperature, heavy-metal-free homologation of a carbon chain using CO as a C1-source showing for the first time that transition-metal catalysts are not required for Fischer-Tropsch-type reactivity. Reaction of an alkylborane in the presence of either LiHBEt3 or LiAlH4 resulted in multiple CO insertion/reduction events to afford elongated chains by more than two methylene (-CH2-) units, affording aldehyde products upon oxidative aqueous workup. Theoretical and experimental mechanistic studies indicate that the boron terminus is responsible for CO incorporation as well as sequential hydride delivery leading to reduction of acylborane intermediates to alkylboranes.

Cyanide-Free One-Pot Synthesis of Methacrylic Esters from Acetone.

Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3 CH2 , and n-C6 F13 CH2 CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6 F13 CH2 CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4 , with DBU in acetonitrile afforded deuterated MMA (MMA-d8 ) in 70 % yield.

Iron-catalysed homo- and copolymerisation of propylene: steric influence of bis(imino)pyridine ligands.

A series of iron complexes bearing a bis(imino)pyridine ligand were synthesised and examined as precatalysts for homopolymerisation of propylene. The alkyl substituents attached to the aryl group on the imine nitrogen atoms significantly affected the catalytic activity and molecular weight of the obtained polypropylenes. Copolymerisation of propylene and various allyl comonomers catalysed by iron/bis(imino)pyridine was also investigated.