Cycloadducts of Arynes with 1,3-Bis(trimethylsilyl)naphthofuran: Formation of Novel Polycyclic Aromatic Derivatives and Related Reactions

Article abstract of DOI:10.1021/jo00366a015

A recently developed procedure for the preparation of trimethylsilylated isobenzofurans and the use of these materials in cycloaddition reactions has been extended to an isonaphthofuran analogue.The 1,3-bis(trimethylsilyl)naphtho<1,2-c>furan (7) has been isolated; its reaction with maleic anhydride in room temperature is rapid and readily reversible as shown by endo to exo cycloadduct interconversion.The failure of 7 to give cycloadduct with 2-butenolide indicates that it is less reactive than the parent naphtho<1,2-c>furan.In situ generation and cycloaddition reactions with various arynes (benzyne, 4-methylbenzyne, 3,4-pyridyne, 9,10-phenanthrolyne, 1,2-naphthalyne, 2,3-naphthalyne) are described.The three unsymmetrical arynes all give mixtures of cycloadducts indicative of negligible regioselectivity in Diels-Alder reactions with 7; thus, in spite of possible steric hindrance the reaction with 1,2-naphthalyne gives a 1:1 mixture of dibenz- and dibenzanthracene derivatives.In contrast, the reaction of 1-ethoxy-3-(trimethylsilyl)naphtho<1,2-canthracene derivative.Various reactions of the cycloadducts are described.