Organocatalytic Regioselective Synthesis of Sulfur-Containing N-Alkyl Carbamates from Alkyne-Derived Cyclic Carbonates

A highly regioselective synthesis of sulfur-containing N-alkyl carbamate from propargyl alcohol, carbon dioxide (CO 2 ) and amine via metal-free catalysis is described.The regioselective ring-opening addition of tri-substituted cyclic carbonate with amine was investigated in detail.A key feature of this system is the ability to afford tertiary β-hydroxyl N-alkyl carbamate with 100% selectivity by using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst in a wide range of reaction temperatures.The steric hindrance of amine and the use of ethanol favored the regioselective ring-opening addition reaction.A proposed mechanism for the ring-opening addition elaborated the underlying reason for the regioselective synthesis of sulfur-containing N-alkyl carbamate.This study provides a new alternative synthetic route to sulfur-containing N-alkyl carbamates from alkyne and CO 2 and may offer an attractive scaffold for further synthesis.