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Polyurethane (PU) thermoplastics and thermosets were prepared through the step-growth polymerization of in situ generated polyisocyanates through the decarboxylation of polyoxamic acids, in the presence of phenyliodine diacetate (PIDA), and polyols. The CO 2 produced during the reaction allowed the access to self-blown polyurethane foams through an endogenous chemical blowing. The acetic acid released from ligand exchange at the iodine center was also shown to accelerate the polymerization reaction, avoiding the recourse to an additional catalyst. Changing simple parameters during the production process allowed us to access flexible PU foams with a wide range of properties., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Oxamic acids where shown to add to imines, providing a broad range of α-aminoacid amides in generally good yields. The process is efficient on pre-formed imines but may also be conducted using a 3-component strategy by simply mixing aldehydes, amines and oxamic acids in the presence of ferrocene, acting both as a photocatalyst under visible light and as a Lewis acid. The reaction proceeds through the addition onto the imine of a carbamoyl radical intermediate generated through a charge transfer from the carboxylate ligand to a Fe(iii) species (LMCT)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Dual Ni and Ir catalysis enables the preparation of arylsilanes having a (TMS) 3 Si substituent from the corresponding aryl bromides and (TMS) 3 SiH at 30 °C using visible-light irradiation. This protocol avoids strong bases, high temperature and air and moisture sensitive silyl reagents, providing the expected arylsilanes in moderate to good yields. The reaction was shown to proceed through a silyl radical, likely generated by hydrogen atom abstraction from (TMS) 3 SiH by a bromide radical.

Photocatalyzed oxidative decarboxylation of oxamic acids under near-infrared irradiation using Os(bptpy) 2 (PF 6 ) 2 as catalyst is reported. The reaction was applied to the synthesis of urethanes and heterocyclic amides. Mechanistic studies and comparative penetration depths between the NIR and the visible light mediated processes are discussed.

This review article describes the recent development in the chemistry of carbamoyl radicals generated from oxamic acids. This mild and efficient method compares well with previous methods of generation of these nucleophilic radicals. The oxidative decarboxylation of oxamic acids can be mediated through thermal, photochemical, electrochemical or photoelectrochemical means, generating carbamoyl radicals, which may further add to unsaturated systems to provide a broad range of important amides. Oxidative decarboxylation of oxamic acids also offers a straightforward entry for the preparation of urethanes, ureas, and thioureas.

A new efficient strategy to access benzylic carbamates through C-H activation is reported. The use of a catalytic amount of a Cu(i)/diimine ligand in combination with NFSI ((PhSO2)2NF) or F-TEDA-PF6 as oxidants and H2NCO2R as an amine source directly leads to the C-N bond formation at the benzylic position. The mild reaction conditions and the broad substrate scope make this transformation a useful method for the late-stage incorporation of a ubiquitous carbamate fragment onto hydrocarbons.

Urethane synthesis via oxidative decarboxylation of oxamic acids under mild electrochemical conditions is reported. This simple phosgene-free route to urethanes involves an in situ generation of isocyanates by anodic oxidation of oxamic acids in an alcoholic medium. The reaction is applicable to a wide range of oxamic acids, including chiral ones, and alcohols furnishing the desired urethanes in a one-pot process without the use of a chemical oxidant.

The generation of carbamoyl radicals, followed by their addition to heteroarenes, was performed under mild conditions through a metal-free photocatalyzed decarboxylation of oxamic acids. The process has been applied to the carbamoylation of heteroaromatic bases using α-aminoacid-derived oxamic acids, leading to the corresponding amides without racemization.

A sustainable metal-free route to urethanes and ureas based on a photocatalyzed oxidative decarboxylation of oxamic acids is described. The reaction includes in situ generation of an isocyanate from the oxamic acid, using an organic dye as a photocatalyst, a hypervalent iodine reagent as an oxidant and a light source, which trigger the free-radical decarboxylation. This protocol successfully avoids the isolation, purification and storage of carcinogenic isocyanates and allows elaboration of urethanes and ureas in a one-pot process from commercially available sources.

A straightforward access to the C10-C20 skeleton of gymnodimine, incorporating a tetrahydrofuran fragment, is described. The elaboration of the THF moiety is based on a stereocontrolled Ueno-Stork cyclization. A Lewis-acid mediated allylation of the resulting acetal at C13 and a Horner-Wadsworth-Emmons olefination on the ketone at C17 complete the synthesis.

Desymmetrization of 7-silylcycloheptatriene through consecutive dihydroxylation and acyl-nitroso cycloaddition of the resulting diene moiety is described. Dihydroxylation occurred anti relative to the resident silicon group in line with previous observations made in the cyclohexadiene series. In contrast, the subsequent acyl-nitroso cycloaddition occurred with poor regiocontrol but good level of diastereocontrol syn to the bulky silyl substituent. The resulting cycloadducts were then elaborated further to provide a straightforward entry toward aminocycloheptitols in ten steps from commercially available tropylium salts.

A concise enantioselective route to isotetronic acids using an organocatalyzed aldol reaction between alpha-oxocarboxylic acids and aldehydes has been developed, leading to the titled compounds in reasonable yields and good enantioselectivities.