this invention relates to several intermediates useful in preparing thromboxane a 2 inhibiting 7 -- thioxomethyl ] hydrazono ] ethyl ]- 1 . alpha ., 4α - bicyclohept - 2β - yl ]- heptenoic acids and useful derivatives thereof from octahydro - 1α - methyl - 3aα , 7aα - 4α , 7α - methano - 2h - inden - 2 - ones .