Getting a fix: N-heterocyclic carbenes (NHCs) and NHC-CO(2) adducts serve as potent organocatalysts for carbonate synthesis by the addition of a CO(2) unit to propargylic alcohols or epoxides under mild and solvent-free reaction conditions (see scheme). The enhanced Lewis basicity of imidazol-2-ylidenes bearing electron-donating alkyl groups on the nitrogen atoms leads to utilizing CO(2) as a nucleophilic fragment in the chemical fixation processes.

Newly developed oxo-tethered Ru amido complexes (R,R)-1 and their HCl adducts (R,R)-2 exhibited excellent catalytic performance for both asymmetric transfer hydrogenation and the hydrogenation of ketonic substrates under neutral conditions without any cocatalysts to give chiral secondary alcohols with high levels of enantioselectivity.

A series of 16-electron Cp*Ir amide complexes with C-N chelating ligands, Cp*Ir[κ 2 (N,C)-(NHCR 2 -2-C 6 H 4 )] (2a: R ) C 6 H 5 , 2b: R ) CH 3 ), and the chiral version, Cp*Ir[κ 2 (N,C)-(R)-{NHCH(CH 3 )-2-C 10 H 6 }] (2e), were obtained in good to excellent yields from reactions of 18-electron iridium amine complexes, Cp*IrCl[κ 2 (N,C)-(NH 2 CR 2 -2-C 6 H 4 )] (1a: R ) C 6 H 5 , 1b: R ) CH 3 ) and Cp*IrCl[κ 2 (N,C)-(R)-{NH 2 CH(CH 3 )-2-C 10 H 6 }] ( 1e), with a base. The amido complexes 2 readily reacted with 2-propanol to convert into hydrido(amine) complexes 3 in almost quantitative yields. The chiral amido complex has proven to serve as an efficient catalyst for asymmetric transfer hydrogenation of acetophenone with 2-propanol, giving 1-phenylethanol with a moderate ee. The Brønsted basicity on the metal-NH moiety in the amido complexes was evaluated by deprotonation of acetic acid, dimethyl malonate, and acetone, leading to the corresponding acetato(amine) complex 4 and alkyl(amine) complexes 5 and 6, respectively, indicating that the amido-Ir complexes bearing the C-N chelate have more basic properties than those with N-sulfonylated diamine ligands.

A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η(6)-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and triethylamine with an unprecedented level of excellent enantioselectivity. For the non-ortho-substituted benzophenones, the oxo-tethered catalyst electronically discerned biased substrates, resulting in attractive performance yielding chiral diarylmethanols with >99% ee.

Under pressure: Temperature‐dependent optical transmission in aqueous solution is exhibited by polyurethanes that are obtained by copolymerization of 2‐methylaziridine and supercritical CO2 (scCO2; see scheme). The transmittance drops sharply at the lower critical solution temperature (LCST). The molecular weight, content of urethane linkages, and LCST value of the polyurethanes are controllable simply by changing the CO2 pressure.