Cycloaddition reaction of spiro[2.4]hepta-4,6-dien-1-ylmethanol and PTAD: a new rearrangement

Abstract Reaction of spiro[2.4]hepta-4,6-dien-1-ylmethanol (3) with phenyltriazolinedione (PTAD) gave 4-phenyl-1-[(3a R ( S ),6 S ( R ))-1a, 2,3a, 6-tetrahydro-1 H -cyclopenta[ b ]cyclopropa[ c ]furan-6-yl]-1,2,4-triazolidine-3,5-dione ( 7 ) via a novel rearrangement. The structure of this rearranged product was determined by spectroscopic methods and by experimentation. Influences of functional groups on the rearrangement and formation of 7 were discussed.