Different addition modes of cyclopentadiene and furan at methylidene(thio)hydantoins

Diffusion mixing with a volatile tertiary amine as a very efficient technique for 1,3-dipolar cycloaddition reactions proceeding via dehydrohalogenation of stable precursors of reactive dipoles

“…Unsymmetrical norbornene derivative 4 , obtained by the method, 42 reacts with an excess of halogen derivatives 6 and 7 to form heterocycles 12 and 13 , respectively, in good yields. The exo -configuration of compounds 12 and 13 was determined from the value of the spin–spin interaction constants of the CH groups in the norbornane backbone.…”

“…Norbornene derivative 4 and Nmethylidenehidantoin 5 were obtained using the procedures described in the literature. 42,44 Experimental details for the preparation of hydroximoyl halides 6a-c and imidoyl chlorides 6d and e have been previously described. [45][46][47][48][49] Reactions were checked by TLC analysis using silica plates with a fluorescent indicator (254 nm) and visualized with a UV lamp.…”