01533nas a2200169   4500008004100000022001400041245015500055210006900210260000800279300001400287490000700301520085700308100002301165700002401188700002201212856012901234       2019                        eng d  a1477-052000aTiCl4-n-Bu3N-mediated cascade annulation of ketones with alpha-ketoesters: a facile synthesis of highly substituted fused gamma-alkylidene-butenolides0 aTiCl4nBu3Nmediated cascade annulation of ketones with alphaketoe  cJUN  a5749-57590 v173 a<p>A facile protocol for the synthesis of highly substituted fused gamma-alkylidene butenolides using direct annulation of ketones with alpha-ketoesters, which proceeds through TiCl4-n-Bu3N mediated aldol addition followed by an intramolecular enol-lactonization/cyclization cascade, is reported. Diverse 6-5, 7-5 and 8-5 fused bicyclic gamma-ylidene butenolides and highly substituted monocyclic analogs related to biologically relevant natural products were prepared from readily accessible ketone and alpha-ketoester building blocks. The highly step-economic cascade nature, good substrate scope, easy access to complex products with good to excellent yields, gram-scalability, demonstration of synthetic utility, and unambiguous structural confirmation through X-ray crystallography analyses and analogy are the salient features of this work.</p>
1 aPalange, Megha, N.1 aGonnade, Rajesh, G.1 aKontham, Ravindar  uhttps://library.ncl.res.in/content/ticl4-n-bu3n-mediated-cascade-annulation-ketones-alpha-ketoesters-facile-synthesis-highly