Polyamide monomers via carbonate-promoted C-H carboxylation of furfurylamine.

Inedible biomass (lignocellulose) is a largely untapped resource for polymer production because it is synthetically challenging to convert to useful monomers. Here we describe streamlined syntheses of two polyamide monomers from furfurylamine, one of very few chemicals made industrially from lignocellulose. Using carbonate-promoted C-H carboxylation, furfurylamine is converted into a furan-containing amino acid and a tetrahydrofuran-containing bicyclic lactam in two and four steps, respectively. Our syntheses avoid the use of protecting groups and multiple stoichiometric organic reagents required by previous, longer routes to these targets. This work facilitates access to furan- and tetrahydrofuran-based polyamides, which are unavailable from petrochemical feedstocks.

Enantioenrichment of a tungsten dearomatization agent utilizing chiral acids.

A method is described for the resolution of the versatile dearomatization reagent TpW(NO)(PMe3)(η(2)-benzene), in which the 1,3-dimethoxybenzene (DMB) analogue of this complex is synthesized. In turn, the coordinated arene of TpW(NO)(PMe3)(DMB) is protonated with either D or L dibenzoyl tartaric acid (DBTH2) in a butanone/water or 2-pentanone/water solution. Sustained stirring of this mixture results in the selective precipitation of a single form of the diastereomeric salt [TpW(NO)(PMe3)(DMBH)](DBTH). After isolation, the salt can be redissolved, and the DMB ligand can be deprotonated and exchanged for benzene to produce the desired product TpW(NO)(PMe3)(η(2)-benzene) in either its R or S form. The absolute configuration of the tungsten stereocenter in TpW(NO)(PMe3)(η(2)-benzene) can be determined in either case by substituting the naturally occurring terpene (S)-ß-pinene for benzene and evaluating the 2D NMR spectrum of the corresponding ß-pinene complex.