In Situ Generation of tert ‐Butyl Carbonate From Boc ₂ O Enables Synthesis of Cyclic Carbonates Under Mild Conditions

A mild and efficient one‐pot strategy for synthesizing five‐membered cyclic carbonates has been developed using Boc 2 O as a carbon dioxide surrogate. This transformation proceeds under ambient conditions without metal catalysts, tolerating a wide range of aryl, alkyl, and heteroatom‐substituted epoxides. The studies reveal that tert ‐butyl carbonate, formed in situ from Boc 2 O and amines, undergoes nucleophilic epoxide ring opening followed by intramolecular acyl substitution. The addition of TBAB significantly enhances reactivity, likely by stabilizing ionic intermediates. The protocol affords good to excellent yields (up to 99%) and maintains high enantiopurity for chiral substrates. This operationally simple and scalable method provides an attractive alternative to traditional CO 2 fixation routes and demonstrates the synthetic utility of Boc 2 O beyond its conventional role as a protecting agent.