DIPOLAR CYCLOADDITIONS OF MESOIONIC COMPOUNDS WITH 2-TERT-BUTYLFULVENES - A NEW ROUTE TO PSEUDO-HETERO-AZULENES VIA STERICALLY ASSISTED [4-PI-PI] CYCLOADDITIONS, AND ISOMERIZATION OF ADDUCTS(6)
H. Kato et al., DIPOLAR CYCLOADDITIONS OF MESOIONIC COMPOUNDS WITH 2-TERT-BUTYLFULVENES - A NEW ROUTE TO PSEUDO-HETERO-AZULENES VIA STERICALLY ASSISTED [4-PI-PI] CYCLOADDITIONS, AND ISOMERIZATION OF ADDUCTS(6), Tetrahedron, 53(29), 1997, pp. 9921-9934
Several mesoionic compounds react with 2-tert-butylfulvene derivatives
to form [4 pi+6 pi] and/or [4 pi+2 pi] cycloadducts. They undergo fur
ther fragmentation elimination or isomerization under the reaction con
ditions to give a variety of products including several condensed hete
rocycles which are isoelectronic with azulene. An oxazolium-4-olate, o
n contact with a small amount of air was found to form a tricyclic oxy
genated dimer. (C) 1997 Elsevier Science Ltd.