Potassium Fluoride/Basic Alumina as Far Superior Heterogeneous Catalyst for the Chemoselective Conjugate Addition of Nitroalkanes to Electron-Poor Alkenes Having Two Electron-Withdrawing Groups in α- and β-Positions
作者:Roberto Ballini、Alessandro Palmieri
DOI:10.1002/adsc.200606105
日期:2006.7
The chemoselective, conjugateaddition of nitroalkanes to electron-poor alkenes, with two electron-withdrawing groups in the α- and β-positions, can be easily performed at room temperature under solventlessconditions using potassium fluoride/basicalumina as heterogeneous catalyst.
The first base-free catalyticWittigreaction utilizing readily available Bu3P (5 mol %) as an organocatalyst is reported. The initial Michael addition of the phosphine to a suitable acceptor substituted alkene ultimately results in the formation of an ylide which is subsequently converted with an aldehyde. The presented 1H NMR studies actually reveal evidence for the Michael addition and proposed
报道了利用容易获得的Bu 3 P(5mol%)作为有机催化剂的第一无碱催化Wittig反应。将膦最初加成到合适的受体取代的烯烃上的迈克尔最终加成最终形成叶立德,其随后被醛转化。提出的1 H NMR研究实际上揭示了迈克尔加成反应和拟形成的内鎓盐的证据。在优化的反应条件下,将各种马来酸酯和富马酸酯用芳族,杂芳族和脂族醛进行转化,以评估这种前所未有的反应的范围和局限性。值得注意的是,马来酸盐和富马酸盐以立体会聚的方式反应。以高达95%的分离产率和E获得了相应的产物/ Z选择性高达99:1。
Simultaneous presence of unsaturation and long alkyl chain at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si10.gif" overflow="scroll"><mml:mrow><mml:msubsup><mml:mrow><mml:mtext>P</mml:mtext></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math> of Ilomastat confers selectivity for gelatinase A (MMP-2) over gelatinase B (MMP-9) inhibition as shown by molecular modelling studies
Structural analogues of Ilomastat (Galardin (R)), containing unsaturation(s) and chain extension carrying bulky phenyl group or alkyl moieties at P-1(') were synthesized and purified by centrifugal partition chromatography. They were analyzed for their inhibitory capacity towards MMP-1, MMP-2, MMP-3, MMP-9 and MMP-14, main endopeptidases involved in tumour progression. Presence of unsaturation(s) decreased the inhibitory potency of compounds but, in turn increased their selectivity for gelatinases. 2b and 2d derivatives with a phenyl group inhibited preferentially MMP-9 with IC50 equal to 45 and 38 nM, respectively, but also display activity against MMP-2 IC50 equal to 280 and 120 nM, respectively). Molecular docking computations confirmed affinity of these substances for both gelatinases. With aims to obtain a specific gelatinase A (MMP-2) inhibitor, P, of Ilomastat was modified to carry one unsaturation coupled to an alkyl chain with pentylidene group. Docking studies indicated that MMP-2, but not MMP-9, could accommodate such substitution; indeed 2a proved to inhibit MMP-2 (IC50 = 123 nM), while displaying no inhibitory capacity towards MMP-9. (c) 2007 Elsevier Ltd. All rights reserved.