5-Thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid,7-amino-8-oxo-3-(1-propenyl)-, (6R,7R)-, compd. with2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidine (1:1)