Organocatalytic Methods for Chemoselective O-tert-Butoxycarbonylation of Phenols and Their Regeneration from the O-t-Boc Derivatives
Sunay V. Chankeshwara, Rajesh Chebolu, Asit K. Chakraborti*
*Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar 160062, Punjab, India, Email: akchakrabortiniper.ac.in
S. V. Chankeshwara, R. Chebolu, A. K. Chakraborti, J. Org. Chem., 2008, 73, 8615-8618.
DOI: 10.1021/jo8013325 (free Supporting Information)
Carbon tetrabromide catalyzes O-tert-butoxycarbonylation of functionalized phenols without any side reactions (bromination, addition of CBr3 to a double bond, and formation of symmetrical diaryl carbonates, cyclic carbonates, or carbonic-carbonic anhydrides). The parent phenols are regenerated from the O-t-Boc derivatives by the catalyst system CBr4-PPh3 without affecting other functional groups.
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R. Chebolu, S. V. Chankeshwara, A. K. Chakraborti, Synthesis, 2008, 1448-1454.