title: Synthesis of complex benzenoids via the intermediate generation of o-benzynes through the hexadehydro-Diels-Alder reaction.
abstract: The hexadehydro-Diels-Alder (HDDA) cascade enables the synthesis of complex benzenoid products with various substitution patterns through aryne intermediates. The first stage of this cascade involves the generation of a highly reactive ortho-benzyne intermediate by a net [4+2] cycloisomerization of a triyne substrate. The benzyne can be rapidly 'trapped' either intramolecularly or intermolecularly with myriad nucleophilic or π-bond-donating reactants. As a representative example of a general procedure for synthesizing highly substituted benzenoids, this protocol describes the synthesis of a typical triyne substrate and its use as the reactant in an HDDA cascade to form a phthalide. The synthetic procedure detailed herein (four chemical reactions) takes 16-20 h of active effort over a period of several days for the preparation of the triyne precursor and ∼2 h of active effort over a 3-d period for the generation and trapping of the benzyne and isolation of the phthalide product.
authors: Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA.
authors: Beeraiah
authors: B
authors: Baire
authors: Dawen
authors: D
authors: Niu
authors: Patrick H
authors: PH
authors: Willoughby
authors: Brian P
authors: BP
authors: Woods
authors: Thomas R
authors: TR
authors: Hoye
mesh_terms: D001555:Benzene Derivatives / Q000138:chemical synthesis*; D001572:Benzofurans / Q000138:chemical synthesis; D061565:Cycloaddition Reaction / Q000379:methods*; D015394:Molecular Structure
chemical_list: D001555:Benzene Derivatives; D001572:Benzofurans; C524146:benzyne; C082022:phthalide