Simple, secondary 2,4,6-triisopropyl benzoates (TIB esters) and secondary dialkyl N,N-diisopropyl carbamates have been reported to be resistant to deprotonation by strong bases. We have found that the combination of sBuLi (1.6 equiv) and TMEDA (6 equiv) in CPME at -60 C enables deprotonation of unactivated secondary dialkyl TIB esters, but not the carbamates. 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 universally high er. Further functional group transformations of the tertiary boronic esters were demonstrated (conversion to quaternary centers, C-tertiary amines) together with application of the methodology to the synthesis of the simplest unbranched hydrocarbon bearing a quaternary center, (R)-4-ethyl-4-methyloctane, validating the synthetic utility of the methodology. © 2013 American Chemical Society.
CITATION STYLE
Pulis, A. P., Blair, D. J., Torres, E., & Aggarwal, V. K. (2013). Synthesis of enantioenriched tertiary boronic esters by the lithiation/borylation of secondary alkyl benzoates. Journal of the American Chemical Society, 135(43), 16054–16057. https://doi.org/10.1021/ja409100y
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