Formation of 1,3,4,5-tetraphenyl-2,6,7-trioxabicyclo[3.2.1]oct-3-ene from the ozonolysis of 1,2,3,4-tetraphenyl-1,3-cyclopentadiene. First [3 + 4] addition of a carbonyl oxide moiety to an .alpha.,.beta.-unsaturated carbonyl group