Mild and chemoselective catalytic deprotection of ketals and acetals using cerium(IV) ammonium nitrate
作者:Ali Ates、Arnaud Gautier、Bernard Leroy、Jean-Marc Plancher、Yannick Quesnel、Jean-Christophe Vanherck、István E Markó
DOI:10.1016/j.tet.2003.03.002
日期:2003.11
Cerium(IV) ammonium nitrate (CAN) is a powerful, though mild, reagent for the efficient and selective removal of a range of ketals and acetals. This novel deprotection method requires only catalytic amounts of CAN and tolerates a variety of functional and protecting groups. Mechanistic insights suggest that the Ce(IV) salts act as unique Lewis acids and not as redox active species.
Lewis acid catalyzed rearrangements of structurally related α,β-unsaturated epoxy ketones and oximes. A complementary approach to the synthesis of isomeric 1,4-diketospiro[n,m] alkanes.
作者:Robert D. Bach、Mark W. Tubergen、Russell C. Klix
DOI:10.1016/s0040-4039(00)84850-9
日期:1986.1
Lewis acid catalyzed rearrangement of α,β-epoxy oximes proceeds by oxirane cleavage α to the oxime moiety with an attendant pinacol type alkyl migration to the resonance stabilized carbenium ion at Cα, affording a 1,3-diketo-monoxime.
Photochemische Reaktionen. 71. Mitteilung. Die Photoisomerisierung eines spirocyclischen α, β-Epoxyketons
作者:H. J. Wüthrich、A. Siewinski、H. Schaffner、Oskar Jeger
DOI:10.1002/hlca.19730560114
日期:1973.1.31
On direct UV. irradiation and on triplet sensitization with acetophenone the spirocyclic epoxyketone (R)-(−)-9 undergoes racemization (Φ313/334 0.014, ΦSens 0.0060) and rearrangement to the enantiomeric spiro-β-diketones (R)-(+)-14 (Φ313/334 0.068, ΦSens 0.0037) and (S)-(−)-14 (Φ313/334 0.024, ΦSens 0.0023). The quantum yield data show that triplet reaction due to intersystem crossing is unimportant