Synthesis ofN-Boc-α-amino Acids from Carbon Dioxide by Electrochemical Carboxylation ofN-Boc-α-aminosulfones
Electrochemical reduction ofN-Boc-α-aminosulfones in DMF using an undivided cell equipped with a Pt plate cathode and an Mg rod anode under atmospheric pressure of bubbling carbon dioxide through the solution under constant current conditions resulted in a reductive C-S bond cleavage with elimination of benzenesulfinate ion generating the corresponding anion species followed by fixation of carbon dioxide to give the correspondingN-Boc-α-amino acids in moderate to good yields.
Senboku, Hisanori,Minemura, Yoshihito,Suzuki, Yuto,Matsuno, Hidetoshi,Takakuwa, Mayu
p. 16077 - 16083
(2021/10/12)
Synthesis of arylglycine and mandelic acid derivatives through carboxylations of α-amido and α-acetoxy stannanes with carbon dioxide
Incorporation reactions of carbon dioxide (CO2) with N-Boc-α-amido and α-acetoxy stannanes were developed using CsF as a mild tin activator. Monoprotected α-amido stannanes could be used, and the corresponding arylglycine derivatives were obtained in moderate-to-high yields under 1 MPa (10 atm) of CO2 pressure. α-Acetoxy stannanes also underwent carboxylation to afford mandelic acid derivatives in excellent yields under ambient CO2 pressure. Both transformations enabled the synthesis of α-tertiary and α-quaternary carboxylic acid derivatives. In addition, the chirality of (S)-N-tert-butylsulfonyl-α- amido stannanes was transferred with up to 90% inversion of configuration at 100 °C.