Wanzlick‐Carbene in der [4 + 1]‐Cycloaddition mit Bis(methylthio)‐ und Bis(trifluormethyl)‐1,2,4,5‐tetrazin

Abstract

Wanzlick Carbenes in the [4 + 1] Cycloaddition Reaction with Bis(methylthio)‐ and Bis(trifluoromethyl)‐1,2,4,5‐tetrazineThe 3,6‐disubstituted 1,2,4,5‐tetrazines 3 and 4 have been submitted to a [4 + 1] cycloaddition reaction with the nucleophilic singlet carbenes (Wanzlick carbenes) 2a–d, which are generated from the precursors 1a–d. With 3 as diazadiene the expected spiro compounds 6a–d are formed. In contrast to this presumed two‐step reaction sequence of 3, with the tetrazine 4 the cascade cycloaddition/cycloelimination is surprisingly followed by an intramolecular electrophilic aromatic substitution to yield the chiral tetracyclic compounds of type 8 with high diastereoselectivity. The crystal structure of 8d has been determined by X‐ray diffraction methods.