Constructing the architecturally distinctive ABD-tricycle of phomactin A through an intramolecular oxa-[3+3] annulation strategy
作者:Grant S. Buchanan、Kevin P. Cole、Gang Li、Yu Tang、Ling-Feng You、Richard P. Hsung
DOI:10.1016/j.tet.2011.09.111
日期:2011.12
Our efforts in constructing the ABD-ring of phomactin A through an intramolecular oxa-[3+3] annulation strategy is described. This struggle entailed finding a practical and efficient preparation of annulation precursor, and a realization of the unexpected competing regioisomeric pathway. The success entailed accessing the A-ring through Diels Alder cycloaddition of Rawal's diene. Furthermore, the discovery that the regioisomers from the annulation existed as atropisomers with respect to the D-ring olefin and that they could be equilibrated to the desired ABD-tricycle, allowing large quantities of tricycle to be accessed. Published by Elsevier Ltd.
A radical based addition–elimination route for the preparation of indoles
作者:John A. Murphy、Karen A. Scott、Rhona S. Sinclair、Concepcion Gonzalez Martin、Alan R. Kennedy、Norman Lewis
DOI:10.1039/b002565h
日期:——
Indoles, including tricyclic derivatives, are produced by cyclisations of aryl radicals onto vinyl halides followed by elimination of halide radical and tautomerism of the resulting product; the aryl radicals are produced using âclean methodologyâ either by reaction of iodide ions with arenediazonium salts or by reaction of phosphorus-centred radicals with aryl iodides.
Copper-Free Asymmetric Allylic Alkylation Using Grignard Reagents on Bifunctional Allylic Bromides
作者:David Grassi、Alexandre Alexakis
DOI:10.1021/ol300299b
日期:2012.3.16
A series of substrates containing a vinylic bromide were employed in a copper-free methodology using bidendate NHC ligands. The desired compounds are generally obtained with good enantioselectivity and good regioselectivity. Importantly the copper-catalyzed system afforded a lower enantioselectivity value. The catalytic products could be transformed into a broad scope of new 1,1-disubstituted olefins