Synthesis of Enantioenriched Tertiary Boronic Esters by the Lithiation/Borylation of Secondary Alkyl Benzoates
Alexander P. Pulis, Daniel J. Blair, Eva Torres and Varinder K. Aggarwal*
*School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K., Email: v.aggarwalbristol.ac.uk
A. P. Pulis, D. J. Blair, E. Torres, V. K. Aggarwal, J. Am. Chem. Soc., 2013, 135, 16054-16057.
DOI: 10.1021/ja409100y (free Supporting Information)
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The combination of sBuLi and TMEDA in CPME at -60 °C enables deprotonation of unactivated, chiral secondary dialkyl TIB esters. These carbanions were reacted with a range of neopentyl boronic esters which, after 1,2-metalate rearrangement and oxidation, gave a range of tertiary alcohols in high yield and high ee. Further functional group transformations of the tertiary boronic esters were demonstrated.
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S. Nave, R. P. Sonawane, T. G. Elford, V. K. Aggarwal, J. Am. Chem. Soc., 2010, 132, 17096-17098.