Dibromocarbonyl Ylides. Deoxygenation of Aldehydes and Ketones by Dibromocarbene

Article abstract of DOI:10.1021/jo00172a015

The reaction of phenyl(tribromomethyl)mercury (4) with benzaldehyde-α-¹³C results in benzal-α-¹³C bromide and CO.The generality of this deoxygenation was shown by treatment of other aldehydes and ketones with mercurial 4 (1.8:1, benzene, 80 deg C, 4 h): , Ph (46), Et (35), i-Pr (39), t-Bu (19); Ph, Ph (6), Ph, Me (15), Me, Me (16), Et, n-Bu (19), Me, c-C3H5 (20), c-C3H5, c-C3H5 (20), cyclohexanone (38), cyclopentanone (19), norcamphor (46).Additional products in selected cases include (for acetophenone) α-bromostyrene, (for cyclohexanone) 1-bromocyclohexene and 1,1-dibromocyclohexane, (for norcamphor) 2,2-dibromonorbornane, 1,2-dibromonorbornane, 2-bromo-2-norbornene and 1-bromonorbornene, and (for pivaldehyde) 1,1-dibromo-2,2-dimethylpropane.The yields of CO from the treatment of a series of benzaldehydes with mercurial 4 (1.8:1 benzene, 80 deg C, 20 h) are given in parentheses: ArCHO (percent CO), 4-MeO (81), 4-Me (61), 3-Me (55), H (50), 4-F (46), 3-MeO (58), 4-Cl (46), 4-Br (47), 3-Cl (34), 3,4-Cl2 (27).A Hammett-type correlation of log (yield)/(yield)₀ vs. ? gave ρ = -0.50 (r = 0.94).