An annulation route to 1,4-dimethoxynaphthalenes

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α-Oxoketene dithioacetals mediated benzoannelation of aromatic heterocycles: an efficient regiocontrolled synthesis of highly substituted and polycyclic benzo[b]thiophenes

An efficient regiocontrolled synthesis of highly substituted and complex polycyclic benzo[b]thiophenes has been developed via our benzoannelation strategy involving conjugate addition-displacement on a variety of α-oxoketene dithioacetals by carbanions derived from 2- and 3-cyanomethylthiophenes followed by acid induced cyclization of the resulting conjugate adducts

An efficient general synthesis of novel functionalized tetrahydroisoquinoline derived enamines via polarized ketene N,S-acetals

An efficient general method for the synthesis of novel functionalized heterocyclic enaminones/esters/nitriles derived from tetrahydroisoquinoline has been developed by HgCl2 (or POCl3) induced cyclocondensation of newly prepared polarized ketene N,S-acetals from 3,4-dimethoxyphenylethylamine and polarized ketene dithioacetals. 1-(substituted-methylene)-1,2,3,4-tetrahydroisoquinolines - polarized ketene N,S-acetals - polarized ketene dithioacetals - heterocyclic enaminones - heterocyclic enaminonitrile

[4 + 2] cycloaromatization of 4-bis(methylthio)-3-buten-2-one with active methylene ketones: a simple and facile phenol annulation

A new method for β-phenol annulation involving base-induced [4C + 2C] cycloaromatization of readily available 4-bis(methylthio)-3-buten-2-one with a variety of cyclic and acyclic active methylene ketones has been reported. Appropriate choice of ketones allows synthesis of diverse frameworks such as dihydroindan, tetrahydronaphthalenes, their higher homologues, dihydro/octahydrophenanthrenes, anthracene, and heteroannulated analogue in high yields with regiocontrol of phenolic functionality

Natural Product-Guided Synthesis of a Spiroacetal Collection Reveals Modulators of Tubulin Cytoskeleton Integrity

The spiro[5.5]ketal moiety forms the underlying structural skeleton of numerous biologically active natural products. Since simplified but characteristic spiroketals derived from the parent natural products retain biological activity, the spiro[5.5]ketal unit can be regarded as a biologically prevalidated framework for the development of natural product-derived compound collections. We report an enantioselective synthesis of spiro[5.5]ketals on solid support. The reaction sequence employs asymmetric boron enolate aldol reactions with the enolate bound to the polymer or in solution as the key enantiodifferentiating step. It proceeds in up to 12 steps on solid support, makes the desired spiroketals available in high overall yields and with high stereoselectivities and is amenable to structural variation of the products. The small spiroketal collection synthesized contains phosphatase inhibitors and compounds that modulate the formation of the tubulin cytoskeleton in human cancer cells without directly targeting microtubules.publishe