Reduction of Tertiary Phosphine Oxides with DIBAL-H
Carl A. Busacca,* Ravinder Raju, Nelu Grinberg, Nizar Haddad, Paul James-Jones, Heewon Lee, Jon C. Lorenz, Anjan Saha and Chris H. Senanayake
*Department of Chemical Development, Boehringer-Ingelheim Pharmaceuticals, Inc., 900 Ridgebury Road, Ridgefield, Connecticut 06877, Email: cbusaccardg.boehringer-ingelheim.com
C. A. Busacca, R. Raju, N. Grinberg, N. Haddad, P. James-Jones, H. Lee, J. C. Lorenz, A. Saha, C. H. Senanayake, J. Org. Chem., 2008, 73, 1524-1531.
DOI: 10.1021/jo7024064 (free Supporting Information)
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Many tertiary phosphine oxides undergo considerable reduction at ambient temperature with diisobutylaluminum hydride and then stall due to inhibition. Source of this inhibition is tetraisobutyldialuminoxane (TIBAO), which builds up as the reaction proceeds and selectively coordinates the TPO starting material. Several strategies have been found to circumvent this inhibition.
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