saturated carbocycle and (b) [3,4-c]-anellation to benzopyrans, towards typical acetylenic dienophiles has been investigated. Because of the absence of conjugation, the thiophenes of type (a) do not undergo [4+2]-cycloaddition with acetylenic dienophiles. Instead, the N-vinylated products 2 and 3 were obtained with dimethyl acetylene dicarboxylate (DMAD). Electron poor alkynes react with the thiophenes of
Diels–Alder cycloaddition of various dienophiles to the bay region of polycyclic aromatic hydrocarbons (PAHs) is a particularly effective and useful tool for the modification of the structure of PAHs and thereby their final properties. The Diels–Alder cycloaddition belongs to the single‐step annulative π‐extension (APEX) reactions and represents the maximum in synthetic efficiency for the constructions
A Novel Multicomponent Reaction of Arynes, β-Keto Sulfones, and Michael-Type Acceptors: A Direct Synthesis of Polysubstituted Naphthols and Naphthalenes
作者:Xian Huang、Jian Xue
DOI:10.1021/jo070241q
日期:2007.5.1
A novel multicomponent reaction of arynes, β-keto sulfones, and Michael-type acceptors is presented, providing an efficient method for the synthesis of polysubstituted naphthols and polysubstituted naphthalenes. Further investigation suggests that the tandemreaction may proceed via a sequential nucleophilic attack to arynes, intramolecular nucleophilic substitution followed by a Michael addition,
By heating aryl aldehydes with catalytic amounts of a rhenium complex, ReBr(CO)(5), and N-phenylacetamide in toluene, indenone derivatives are obtained in good to excellent yields. This reaction proceeds via (1) the formation of an isobenzofuran derivative by the insertion of an aldehyde into the C-H bond of another aldehyde (C-H bond activation) and successive intramolecular nucleophilic cyclization, (2) nucleophilic addition of the formed isobenzofuran derivative to the third aldehyde, (3) isomerization, and (4) intramolecular aldol condensation.