A One‐Pot Synthesis of N‐Aryl‐2‐Oxazolidinones and Cyclic Urethanes by the Lewis Base Catalyzed Fixation of Carbon Dioxide into Anilines and Bromoalkanes

Abstract

The multicomponent assembly of pharmaceutically relevant N-aryl-oxazolidinones through the direct insertion of carbon dioxide into readily available anilines and dibromoalkanes is described. The addition of catalytic amounts of an organosuperbase such as Barton's base enables this transformation to proceed with high yields and exquisite substrate functional-group tolerance under ambient CO2 pressure and mild temperature. This report also provides the first proof-of-principle for the single-operation synthesis of elusive seven-membered ring cyclic urethanes.

Synthesis of cyclic carbonates from diols and CO2 catalyzed by carbenes

“…The efficiency of a variety of bases and alkyl halides was also studied as they are essential for the reaction to proceed (see below). 16 The ability of cesium carbonate (Cs 2 CO 3 ) to activate CO 2 and other small molecules [28][29][30][31][32] encouraged us to employ it as a base in the reaction. Dibromomethane (CH 2 Br 2 ) was also used due its efficiency in forming an effective leaving group.…”

Synthesis of Oxazolidinones and Derivatives through Three‐Component Fixation of Carbon Dioxide

“…Recently, a few three‐component reactions to prepare oxazolidinones from CO 2 have been reported (Scheme ) . The three‐component reaction of amines, ethylene oxide with CO 2 was explored mostly and amino alcohols, phenyl isocyanate and cyclic carbonates have been proposed as intermediate in the catalytic cycle .…”

“…The three‐component reaction of amines, ethylene oxide with CO 2 was explored mostly and amino alcohols, phenyl isocyanate and cyclic carbonates have been proposed as intermediate in the catalytic cycle . Besides, there is one report about three‐component reaction of 1,2‐dibromoethane, anilines with CO 2 . Even though this reaction are carried out under mild conditions, only active and less hindered dibromoalkanes was investigated.…”

Carbon dioxide-based facile synthesis of cyclic carbamates from amino alcohols

“…[15][16][17][18][19][20][21][22][23][24][25][26] Meanwhile, our group has studied the synthesis of cyclic carbamates utilizing haloalkylamines, 27 and the multicomponent reaction between anilines, dihaloalkanes, and carbon dioxide. 28 While certainly more efficient than conventional non-CO 2 -based carbamate syntheses, all these methods have one or more drawbacks, namely the lack of stereoselectivity, 29 toxicity, and commercial unavailability of the starting materials, or the inability to easily access the substitution patterns required for pharmaceuticals.…”

“…Using the simple, inexpensive and commercially available 2-(phenylamino)ethan-1-ol 1a as a model substrate, we first investigated the reaction conditions we had previously employed successfully in the synthesis of N-aryl-2-oxazolidinones from anilines and dibromoalkanes (Table 1, entry 1). 28 However, N-tosylation is heavily favored under these conditions, as the carbamate species is too labile to sufficiently protect the nitrogen from a reaction with TsCl. Indeed, decreasing the temperature and increasing the CO 2 pressure to shift the equilibrium towards carbamate formation ( Table 1, entry 2) leads to a clear increase in selectivity.…”