THE FORMATION OF THE BENZO[f]-3-PHOSPHABICYCLO[3.3.0]OCT-6-ENE RING SYSTEM IN THE FRIEDEL-CRAFTS REACTION OF THE ADDUCTS OF 2,5-DIHYDRO-1H-PHOSPHOLE 1-OXIDES WITH DICHLOROCARBENE

Abstract Depending on the nature of the aromatic substrate the Friedel-Crafts reaction of P-substituted 6,6-dichloro-3-phosphabicyclo[3.1.0]hexane 3-oxides with substituted benzenes may afford two kinds of benzo-phosphabicyclooctene derivatives as well as benzyl-phenyl-hexahydrophosphinine oxides. The formation of the tricyclic products involves the rather rarely occurring opening of the cyclopropane ring, while the benzyl-phenyl-derivatives are formed by ring expansion. Reductive type of Friedel-Crafts reaction is responsible for the formation of a part of the products. In contrast to our earlier proposal the displacement of the two chlorine atoms without the opening of the cyclopropane ring does not take place. The structure of the products was elucidated by 13C, 1H, 31P NMR and mass spectroscopy.