Naoki Ishida, Yasuhiro Shimamoto, and Masahiro Murakami
Angew. Chem. Int. Ed.
Preparation of cyclic carbonates by incorporation of CO2 into strained cyclic systems is well known and widely exploited. A standard synthesis of these compounds is through addition of epoxide into CO2 followed by ring expansion. Murakami and co-workers take a similar approach in cyclic carbonate synthesis in order to demonstrate a process involving 2 goals in green chemistry: CO2 incorporation, and sunlight activation.
The authors show that azetidine derivatives can be prepared from α-methylaminoketones through irradiation with sunlight alone. These high energy intermediates are relatively stable and their stored solar energy can be released in reaction with CO2 under mild conditions. The reaction can tolerate various aryl groups, but chain length is fixed as a hydroxypyrrolidine derivative is too stable to undergo ring opening.