Lithium phosphonate umpolung catalysts: Do fluoro substituents increase the catalytic activity?

• Anca Gliga,
• Bernd Goldfuss and
• Jörg M. Neudörfl

Beilstein J. Org. Chem. 2011, 7, 1189–1197, doi:10.3762/bjoc.7.138

• ; lithium phosphonates; umpolung; Introduction Since the discovery of the cyanide catalyzed benzoin reaction by Liebig and Wöhler in 1832 [1], acyloin-type reactions evolved as powerful tools for couplings of acylanion equivalents with carbon electrophiles. In addition to cyanide [2][3][4][5] and

• nucleophilic carbene catalysts (e.g. thiazolium salts) [6][7][8][9][10][11][12][13][14][15][16][17], lithium phosphonates were found to catalyze cross acyloin type couplings of acylsilanes with aldehydes [18]. The catalytic cycle proposed by Johnson et al. [18] (Scheme 1) suggests that a potential