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.
Efficient and convergent stereocontrolled spiroannulation of ketones
作者:István E. Markó、Jean-Christophe Vanherck、Ali Ates、Bernard Tinant、Jean-Paul Declercq
DOI:10.1016/s0040-4039(03)00573-2
日期:2003.4
Upon treatment with tBuOK/H2O, a variety of ω-halo-β-keto-ketals undergo smooth cyclisation, affording in excellent yields mono-protected [n,m] spiro bicyclic diketones. This transformation is highly stereoselective producing, in all cases, the diastereoisomerically pure spiro derivatives.
用t BuOK / H 2 O处理后,各种ω-卤代-β-酮缩酮均进行平滑环化,从而以优异的收率得到单保护的[n,m]螺双环二酮。在所有情况下,这种转化都是高度立体选择性的,产生非对映异构纯的螺衍生物。