Effective Guanidine‐Catalyzed Synthesis of Carbonate and Carbamate Derivatives from Propargyl Alcohols in Supercritical Carbon Dioxide

Abstract

The reactions of propargyl alcohols with carbon dioxide in supercritical carbon dioxide or in acetonitrile with gaseous carbon dioxide in the presence of organic bases as catalysts have been examined. Bicyclic guanidines are effective catalysts for the formation of a-methylene cyclic carbonates under mild reaction conditions. Oxoalkyl carbonates, oxoalkyl carbamates or a-methyleneoxazolidinones are obtained in high yields and good selectivities in one-step starting from propargyl alcohols and an external nucleophile (alcohols or amines) using bicyclic guanidines as catalysts in supercritical carbon dioxide. Propargylic diols under the same reaction conditions underwent a rearrangement process instead of carbon dioxide insertion whereas in the presence of an external nucleophile the formation of oxocarbonates, oxocarbamates or cyclic carbamates was achieved in satisfactory yields.

Zinc(ii)-catalyzed reactions of carbon dioxide and propargylic alcohols to carbonates at room temperature

“…[9] Reaction of CO2 with propargylic alcohols can obtain α-alkylidene cyclic carbonates efficiently through carboxylative cyclization, which is also a promising and green route to fix CO2. Therefore, many strategies including metal catalyst systems Ru, [10] Co, [11] Fe, [12] Cu, [13] Pd, [14] Ag, [15] tungstate, [16] K2CO3crown ether [17] and metal-free catalyst systems phosphine, [18] bicyclic guanidines, [19] N-heterocyclic carbene/CO2 adduct, [20] N-heterocyclic olefin/CO2 adduct and alkoxide-functionalized imidazolium betaines/CO2 adduct [21] have been reported to synthesize these useful heterocyclic compounds. It was reported recently that some silver catalyst systems such as AgOAc/1, 8diazabicyclo[5.4.0]undec-7-ene (DBU), [15c] Ag2WO4/Ph3P [15f] and [(PPh3)2Ag]2CO3 [15g] can promote the transformation of CO2 into αalkylidene cyclic carbonates effectively.…”

Upgrading Carbon Dioxide by Incorporation into Heterocycles

“…Methods based on the use of transition metals such as ruthenium, [41] palladium, [42] tungsten, [37c] cobalt, [43] copper, [44] iron, [45] and phosphine, [46] N-heterocyclic carbene, [12] K 2 CO 3 /crown ether, [47] organic base/silver salt, [25,48] and bicyclic guanidines [49] have been developed for this purpose. Methods based on the use of transition metals such as ruthenium, [41] palladium, [42] tungsten, [37c] cobalt, [43] copper, [44] iron, [45] and phosphine, [46] N-heterocyclic carbene, [12] K 2 CO 3 /crown ether, [47] organic base/silver salt, [25,48] and bicyclic guanidines [49] have been developed for this purpose.…”

Metal Complexes Catalyzed Cyclization with CO2

“…The addition of a strong base or in some cases an organocatalyst is sufficient to convert propargylic alcohols [85] and propargylic amines [86] to cyclic carbonates and oxazolidinones [87,88], respectively. Although there are various reported examples that concern the use of bases, this work will focus on metal-catalyzed addition reactions that involve CO 2 as a reagent.…”