Development of pinene-derived N,P ligands and their utility in catalytic asymmetric hydrogenation
作者:J. Johan Verendel、Pher G. Andersson
DOI:10.1039/b713257n
日期:——
New diastereomeric N,P-ligands, derived from the natural product (+)-α-pinene, have been synthesized and evaluated in iridium-catalyzed asymmetrichydrogenation. The ligands are tetrahydroquinoline derivatives synthesized directly from commercially available α-pinene utilizing resolution or recrystallization to separate diastereomers. In reduction of a range of different trisubstituted alkenes the
Chiral pyridine N-oxides derived from monoterpenes as organocatalysts for stereoselective reactions with allyltrichlorosilane and tetrachlorosilane
作者:Giorgio Chelucci、Salvatore Baldino、Gerard A. Pinna、Maurizio Benaglia、Laura Buffa、Stefania Guizzetti
DOI:10.1016/j.tet.2008.05.105
日期:2008.8
The synthesis of enantiomerically pure C-2-symmetric dipyridylmethane ligands and related N,N'-dioxides is reported. A procedure for the synthesis of a few new enantiomerically pure C-2-symmetric pyridine N-oxides and the preparation of four pyridine N-oxides with oxygen and nitrogen atoms as further coordinating elements in the heterocycle framework is described. All compounds were prepared from naturally occurring monoterpenes. These new compounds were assessed as organocatalysts in two different reactions, namely the allylation of aldehydes with allyltrichlorosilane that afforded homoallylic alcohols in good yields and up to 85% ee and the stilbene oxide opening by the addition of tetrachlorosilane that gave chlorohydrin in quantitative yield and up to 70% ee. (C) 2008 Elsevier Ltd. All rights reserved.
New monoterpene-derived phosphinopyridine ligands and their application in the enantioselective iridium-catalyzed hydrogenation
作者:Giorgio Chelucci、Mauro Marchetti、Andrei V. Malkov、Frédéric Friscourt、Martin E. Swarbrick、Pavel Kočovský
DOI:10.1016/j.tet.2011.05.075
日期:2011.7
derivatives with a phosphine or phosphinite pendant (1–11) have been synthesized from (+)-α-pinene, (−)-isopinocampheol, and/or (+)-camphor via Kröhnke annulation or another annulation method as the key step for the construction of the pyridine nucleus. The iridium complex of 6 proved to catalyzehydrogenation of the prochiral unfunctionalized alkene 44 with 94% ee, whereas the complex of 2 was most efficient