The use of olefin cross metathesis in preparing functional polymers, through either pre-functionalisation of monomers or post-polymerisation functionalisation is growing in both scope and breadth, as discussed in this review article.

Iron-catalyzed hydromagnesiation of styrene derivatives using ethylmagnesium bromide has been investigated for the synthesis of benzylic Grignard reagents. The benzylic Grignard reagent formed in the reaction was observed directly and its conformation in solution characterized by multinuclear and variable-temperature NMR spectroscopy. The Grignard reagent could be stored for at least 2 weeks without significant loss in activity. Hydromagnesiation of styrene in tetrahydrofuran gave a mixture of monoalkyl-and dialkylmagnesium species, (1phenylethyl)magnesium bromide (2; RMgBr) and bis(1-phenylethyl)magnesium (3; R 2 Mg), with the equilibrium between these species lying in favor of the dialkylmagnesium species. The thermodynamic parameters of alkyl exchange for the reaction MgBr 2 + R 2 Mg (3) ⇌ 2RMgBr (2) were quantified, with the enthalpy and entropy of formation of 2 from MgBr 2 and 3 calculated as 32 ± 7 and 0.10 ± 0.03 kJ mol −1 , respectively. This methodology was applied, on a 10 mmol scale, as the key step in the synthesis of ibuprofen, using sequential iron-catalyzed alkyl−aryl and aryl−vinyl cross-coupling reactions to give 4isobutylstyrene, which following hydromagnesiation and reaction with CO 2 gave ibuprofen. Each step proceeded in excellent yield, at temperatures between 0 °C and room temperature, at atmospheric pressure. Inexpensive, nontoxic, and air-and moisture-stable iron(III) acetylacetonate was used as the precatalyst in each step in combination with inexpensive amine ligands.

Olefin cross metathesis is an effective tool for the functionalization of biodegradable aliphatic polyesters through both pre-and post-polymerization of β-heptenolactone (βHL). Ring opening polymerization of βHL accesses both homopolymers and novel copolymers, producing strong gradient copolymers with lactide. A total of 15 different alkene cross partners ranging from type I to type III olefins are readily incorporated to produce polyesters with a range of functionalities, altering the thermal and chemical

The C-symmetric uranium(iv) and cerium(iv) complexes MeSiOM(OAr), M = U (1), Ce (2), OAr = OCH-6-Bu-4-Me-2-PPh, have been prepared and the difference between these 4f and 5f congeners as initiators for the ring opening polymerisation (ROP) of l-lactide is compared. The poorly controlled reactivity of the homoleptic analogue U(OAr) (3) demonstrates the importance of the M-OSiMe initiating group. The incorporation of a nickel atom in 1 to form the U-Ni heterobimetallic complex MeSiOU(OAr)Ni (4) may be the first example of the use of the inverse trans influence to switch the reactivity of a complex. This would imply the formation of the U-Ni bond strengthens the U-OSiMe bond to such an extent that the ROP catalysis is switched off. Changing the conditions to immortal polymerisation dramatically increases polymerisation rates, and switches the order, with the Ce complex now faster than the U analogue, suggesting ligand protonolysis to afford a more open coordination sphere. For the ROP of rac-lactide, uranium complex 1 promotes heterotacticity at the highest levels of stereocontrol yet reported for an actinide complex.

Poly(lactic acid) is at the forefront of research into alternative replacements to fossil fuel derived polymers, yet preparation of derivatives of this key biodegradable polymer remain challenging. This article explores the use of two derivatives of lactide, each of which features an exocyclic olefin, and their pre‐polymerization modification by olefin cross‐metathesis. Methylenation of lactide with Tebbe's reagent generates a novel 5‐methylenated lactide monomer, (3S,6S)‐3,6‐dimethyl‐5‐methylene‐1,4‐dioxan‐2‐one, complementing the previously reported 3‐methylenated (6S)‐3‐methylene‐6‐methyl‐1,4‐dioxan‐2,5‐dione. While ring‐opening of each monomer is not productive, olefin cross‐metathesis can be used to functionalize each of the exocyclic olefins to produce a family of monomers. The ring‐opening polymerization of these new monomers, and their hydrogenated congeners, is facilitated by organo‐ and Lewis‐acid catalysts. Together, they offer a new strategy for derivatizing and altering the properties of poly(lactic acid). © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 741–748