Switchable synthesis of cyclic carbamates by carbon dioxide fixation at atmospheric pressure

C1 functionalization of imidazo heterocycles via carbon dioxide fixation

Utilizing CO2 as a one-carbon building block in the preparation of high-value chemical entities is a cornerstone of modern organic synthesis. Herein, we exemplify this strategy through a mild, one-pot methodology that gives rapid access to N-heteroaryl substituted 6-, 8- and 9-membered carbamates via CO2 fixation.

Direct access to carbamates via acylation of arylamines with dialkyl azodicarboxylates under metal-free conditions

A novel C-N coupling of various arylamines with dialkyl azodicarboxylates under metal-free conditions for the rapid assembly of carbamates has been achieved. This established protocol features mild reaction conditions, simple operation, broad substrate scope, moderate to excellent yields and good tolerance of functional groups. Moreover, the potential synthetic utility of products was exemplified by a series of intriguing chemical operations.

Base-mediated synthesis of cyclic dithiocarbamates from 1-amino-3-chloropropan-2-ol derivatives and carbon disulfide

An efficient method for the preparation of six-membered cyclic dithiocarbamates is described, in which triethylamine effectively promotes the reaction of 1-amino-3-chloropropan-2-ol derivatives with carbon disulfide. On the basis of the experimental and theoretical studies, a reaction mechanism is proposed to explain the difference between the present reaction and our previously reported carbon dioxide fixation.

Silver-Mediated Cascade Synthesis of Functionalized 1,4-Dihydro-2H-benzo-1,3-oxazin-2-ones from Carbon Dioxide

A conceptually novel catalytic domino approach is presented for the synthesis of highly functional 1,4-dihydro-2H-1,3-benzoxazine-2-one derivatives. Key to the chemoselectivity is a proper design of the precursor to override thermodynamically favored parasitic cyclization processes and empower the formation of the desired product through Thorpe-Ingold effects. The synthetic diversity of these CO₂ -based heterocycles is further demonstrated, and the isolation of a reaction intermediate supports an unusual ring-expansion sequence from an α-alkylidene, five-membered cyclic carbonate to a six-membered cyclic carbamate by N-induced isomerization.

Hydrolysis of a carbamate triggered by coordination of metal ions

The mechanism of carbamate activation promoted by different metal ions has been explored in this work. The reaction of the carbamate ligand H2L with chloride metal salts (M = Ni,...