The aim of this study was to investigate the application of grapeseed oil, a waste product from the wine industry, as a renewable feedstock to make polyesters and to compare the properties of these materials with those derived from soybean and rapeseed oils. All three oils were epoxidized to give renewable epoxy monomers containing between 3.8 and 4.7 epoxides per molecule. Polymerisation was achieved with cyclic anhydrides catalysed by 4-methyl imidazole at 170 and 210 °C. Polymers produced from methyl tetrahydrophthalic anhydride (Aradur917®) had greater tensile strength and Young’s Modulus (tensile strength = 12.8 MPa, Young’s Modulus = 1005 MPa for grapeseed) than methyl nadic anhydride (MNA) derived materials (5.6 and 468 MPa for grapeseed) due to increased volume of MNA decreasing crosslink density. Soybean and grapeseed oils produced materials with higher tensile strength (5.6–29.3 MPa) than rapeseed derived polyesters (2.5–3.9 MPa) due to a higher epoxide functionality increasing crosslinking. Tg’s of the polyesters ranged from −36 to 62 °C and mirrored the trend in epoxide functionality with grapeseed producing higher Tg polymers (−17 to 17 °C) than soybean (−25 to 6 °C) and rapeseed (−36 to −27 °C). Grapeseed oil showed similar properties to soybean oil in terms of Tg, thermal degradation and Young’s Modulus but produced polymers of lower tensile strength. Therefore grapeseed oil would only be a viable substitute for soybean for low stress applications or where thermal properties are more important.

•Cu mediated reaction of 1-substituted enamides occurs via a radical-polar crossover.•Termination can occur via elimination, addition of water or dimerization.•Application of this approach to the indigoid skeleton may be possible.•Methyl migration and aromatization can occur competitively for slow cyclizations.Copper mediated cyclization of activated 1-substituted enamides occurs via a 5-endo radical-polar crossover process. Trichloroacetyl derivatives can undergo further reactions post cyclization (elimination of HCl or dimerization potentially via copper carbenoid intermediates). Reaction of α-halo trienamides derived from β-ionone furnish either β- or γ-lactams via 4-exo or 5-exo cyclizations respectively depending upon the enamide tautomer undergoing reaction. For the less reactive dichloroacetamide derivative a competing regioselective methyl migration-aromatization prior to cyclization is observed.

The barrier to rotation around the N-alkenyl bond of 38 N-alkenyl-N-alkylacetamide derivatives was measured (ΔG⧧ rotation varied between <8.0 and 31.0 kcal mol–1). The most important factor in controlling the rate of rotation was the level of alkene substitution, followed by the size of the nitrogen substituent and, finally, the size of the acyl substituent. Tertiary enamides with four alkenyl substituents exhibited half-lives for rotation between 5.5 days and 99 years at 298 K, sufficient to isolate enantiomerically enriched atropisomers. The radical cyclizations of a subset of N-alkenyl-N-benzyl-α-haloacetamides exhibiting relatively high barriers to rotation round the N-alkenyl bond (ΔG⧧ rotation >20 kcal mol–1) were studied to determine the regiochemistry of cyclization. Those with high barriers (>27 kcal mol–1) did not lead to cyclization, but those with lower values produced highly functionalized γ-lactams via a 5-endo-trig radical–polar crossover process that was terminated by reduction, an unusual cyclopropanation sequence, or trapping with H2O, depending upon the reaction conditions. Because elevated temperatures were necessary for cyclization, this precluded study of the asymmetric transfer in the reaction of individual atropisomers. However, enantiomerically enriched atropsiomeric enamides should be regarded as potential asymmetric building blocks for reactions that can be accomplished at room temperature.

The Lewis acid ring-opening of epoxidized vegetable oils (EVO's) in the presence of tetrahydrofuran (THF) gives rise to polyether polyol co-polymers p(THF-stat-EVO). The effect of Lewis acid, vegetable oil substrate (epoxidised methyloleate EMO, epoxidised cocoa butter ECB, and epoxidised palm oil EPO) and conditions (concentration, temperature and time) on the molecular weight, polydispersity, hydroxyl value and thermal properties of the p(THF-stat-EVO) macromonomers was determined. Elastomeric polyurethanes were prepared from p(THF-stat-EVO) macromonomers and MDI and their mechanical and thermal properties determined. The properties of the polyurethane derived from p(THF-EPO) were compared to that derived from the homopolymer of epoxidised palm oil (EPO) prepared by Lewis acid ring-opening in the absence of THF. The co-polymer incorporating THF gave rise to a material with significantly greater tensile strength [p(THF-EPO-MDI) = 9.1 MPa, p(EPO-MDI) = 1.5 MPa] and elongation at break [p(THF-EPO-MDI) = 425%, p(EPO-MDI) = 70%] with little compromise on thermal stability [p(THF-EPO-MDI) Tdecomp10% = 378 °C, Tdecomp50% = 414 °C, p(EPO-MDI) Tdecomp10% = 379 °C Tdecomp50% = 424 °C].

2-Substituted amidyl radicals derived from 8a–d and 9a–d undergo acyl mode 5-exo-trig cyclisation to give 3,5-trans pyrrolidinones 11a–d and 14a–d as the major products in low diastereoselectivity (de = 9–36%). The steric nature of the nitrogen substituent attached to the amidyl radical does not have a significant effect on selectivity. The stereochemical outcome is opposite to that expected based upon applying the Beckwith rule.

The 4-exo and 5-exo-trig atom-transfer cyclizations of 1, 8a–e, 9, 12, and 13 can be mediated with as little as 0.05 mol % of Cu(TPMA)SO4·5H2O in the presence of 2.5 mol % of borohydride salts in 10 min at room temperature in air. This formal “activators generated by electron transfer” (AGET) procedure utilizes a cheap and oxidatively stable copper source (CuSO4·5H2O) and can be carried out in environmentally benign solvents (EtOH). It is possible to alter the product distribution in the 5-endo radical–polar crossover reactions of 10a,b and 11 by tailoring the amount of borohydride. Cyclization onto alkynes 14 and 15 is also possible in only 20 min. Controlled radical polymerization of styrene, with increased rates over conventional atom-transfer radical polymerization (ATRP), can be carried out in a controlled fashion (Mn, PDI) using either CuBr or CuSO4·5H2O and Bu4NBH4.

Barriers to rotation of the N-alkenyl bond in a series of N-cycloalkenyl-N-benzyl acetamide derivatives have been measured in different solvents by variable-temperature NMR experiments. The barriers range from 9.7 to 14.2 kcal/mol, depending on substituents on the acetamide acyl group. Polar solvents such as chloroform and methanol increase the barrier to rotation compared to nonpolar solvents such as toluene. The barrier to rotation of “mimics” for acetamide-based radicals are estimated. The relative order of the values of krot for different acyl groups parallels their reported Taft Es paramaters. For successful chirality transfer in 5-endo trig radical cyclization, it is evident that rotations would need to be significantly slower than those reported here.

Barriers to rotation of the N-alkenyl bond in a series of N-cycloalkenyl-N-benzyl α-haloacetamide derivatives have been measured by variable-temperature NMR experiments. The barriers range from 10 to 18 kcal/mol, depending on ring size and on substituents on the cycloalkene and the amide. The observed trends aid in the design of substituent combinations that provide resolvable enantiomers or diastereomers at ambient temperature. The compounds undergo 4-exo and 5-endo radical cyclizations at rates that may be faster or slower than the estimated rate of N-alkenyl bond rotation in the derived radicals, depending on the substituents.