A phosgene- and metal-free synthesis of O-aryl carbamates is realized through a three-component coupling of carbon dioxide, amines and diaryliodonium salts. The reaction only requires a base as the promoter, providing access to a diverse array of O-aryl carbamates in moderate to high yields with excellent chemoselectivity.

A. General Remarks 1 H and 13 C NMR spectra were recorded using a Bruker DRX-400 spectrometer using CDCl 3 as solvent and TMS as an internal standard. The chemical shifts are referenced to signals at 7.26 and 77.0 ppm, respectively. IR spectra were obtained either as potassium bromide plates or as liquid films between two potassium bromide plates with a Bruker TENSOR 27 spectrometer. Melting points were determined with a Büchi Melting Point B-545 instrument. All substrates were commercially purchased and used without further purification. Mass spectra were recorded on a Thermo ISQ-II spectrometer at an ionization voltage of 70 eV equipped with a DB-WAX capillary column (internal diameter: 0.25 mm, length: 30 m). B. General procedure for the preparation of dithiocarbamates 3 A 25 mL dried Schlenk tube was charged with boronic acid 1 (0.5 mmol), amine 2 (2.5 mmol), CS 2 (1.0 mmol), Cu(OAc) 2 (1.0 mmol), K 2 CO 3 (1.5 mmol) and MeCN (4 mL) at room temperature. The reaction mixture was stirred at 60 °C for 10 h under air. After the reaction was completed, the mixture was cooled to room temperature and filtered through a plug of celite. The filtrate was then concentrated in vacuo to afford the crude product, which was then subjected to chromatography on silica gel with hexanes/EtOAc (20:1) to give the desired product 3.

A copper-catalyzed four-component formal oxyaminalization of alkenes with Togni’s reagent and amines using molecular oxygen as both the oxidant and oxygen source has been developed for the first time, offering a straightforward and efficient method for the synthesis of a range of structurally diverse α-oxoketene aminals. The use of cheap copper catalyst and readily available substrates, excellent functional group tolerance, broad substrate scope, mild conditions, and simple procedure are the attractive features of the strategy.

A Cu-catalyzed oxidative coupling reaction of arylboronic acids, amines and carbon dioxide is described, providing a route to O-aryl carbamates.

A silver-promoted three-component reaction of carbon dioxide, o-alkynylanilines and diaryliodonium salts using 1,4-diazabicyclo[2.2.2]octane (DABCO) as the base has been developed for the first time, which provides an efficient and straightforward protocol for the synthesis of a wide range of 4-aryloxysubstituted 2-quinolinones in moderate to excellent yields. Diverse functional groups such as halo, trifluoromethyl, cyano and nitro are well tolerated. Mechanistic studies indicated that 4-hydroxyl-2-quinolinone generated in-situ from o-alkynylanilines and carbon dioxide might be the key intermediate for the reaction.2-Quinolinones represent an important class of nitrogencontaining heterocycles frequently found in a variety of biologically active natural products and pharmaceutically interesting compounds, such as 3-O-methylviridicatin, laquinimod and tipifarnib ( Figure 1). [1] Moreover, 2-quinolinones can serve as useful intermediate in various synthetic transformations. [2] Conventionally, 2-quinolinones have been prepared mainly through two methods: a) the reaction of anilines with bdicarbonyl compounds, such as ethyl acetoacetate, [3] malonic esters, [4] malonic acid, [5] or Meldrum's acid; [6] and b) the condensation of o-aminobenzaldehydes [7] or o-aminobenzophenones [8] with b-dicarbonyl compounds. However, these procedures need strong acids or bases and suffer from disadvantages such as limited substrate scope and low efficiency. Therefore, the development of new and efficient methods for the construction of these important molecules is of great significance.In the past decade, many elegant strategies have been developed for accessing different kinds of 2-quinolinones via transition metal catalysis, including intramolecular cyclization reactions via C-C [9] or CÀN bond [10] formation, Pd-catalyzed formal [3 + 3] cyclizations, [11] Ir- [12a] or Ni-catalyzed [12b] [4 + 2] annulations, and Pd-catalyzed [5 + 1] oxidative cyclocarbonylation. [13] Interestingly, Dong et al. reported a Rh-catalyzed [5 + 2 À 1] transformation between isatins and alkynes for the synthesis of 2-quinolinones. [14] Multi-component reaction strategy has also been applied to the synthesis of these rings, such as Pd-or Rh-catalyzed [3 + 2 + 1] [15] and [4 + 1 + 1] [16] reactions.Notably, carbon dioxide (CO 2 ) has recently emerged as an attractive carbonyl source for the construction of 2-quinolinones due to its nontoxicity, abundance and recyclability. [17] For example, the groups of Yamada [18a] and Zhang [18b] independently reported the synthesis of 4-hydroxyquinolin-2(1H)-ones via a silver-or copper-catalyzed incorporation of CO 2 into oalkynylanilines (Scheme 1, a). Yu and co-workers developed a transition-metal-free lactamization of sp 2 CÀH bonds with CO 2 to generate diverse 2-quinolinones under redox-neutral conditions (Scheme 1, b). [18c] Although great progress has been made in this field, to the best of our knowledge, no straightforward approach has been developed for the synthesis of 4-aryloxy-2-quinolinones...