3,3-diphenyl-1,2,5-trioxaspiro[5.5]undeca-7,10-dien-9-one

(9-oxo-1,2,5-trioxaspiro[5.5]undeca-7,10-dien-3-yl) acetate

3,3-diphenyl-1-oxa-spiro[3.5]nona-5,8-diene-2,7-dione

Benzenesulfon-p-anisidide

7,10-epoxy-8,9-dimethoxy-cis-1-transoid-1,10-cis-10-bicyclo[4.4.0]deca-3,8-dien-2,5-dione