Stereochemistry of Mercuric Azide Addition to Cyclopropenes. A Synthesis of Cyclopropyl Azides

Mercuric azide has been shown to add syn to cyclopropenes 3a-d giving the m-2-azidocyclopropylmercuric azide salts 4a-d. Treatment of 4a-d with HBr and NaBr produced the c/j-2-azidocyclopropylmercuric bromide salts 5a-d which were characterized. Reduction of 4a and 4b with NaBH₄ and of 5c with sodium amalgam in H₂O gave the azidocyclopropanes 6a-d. The use of sodium amalgam in D20 in the reduction of 5a-c led to stereospecific replacement of mercury and formation of cis-1 -azido-2- deuteriocyclopropy 1 azides 7a-c. Addition of hydrazoic acid to 3, 3-dimethyl-1-phenylcyclopropene, 3b, also proceeds in a syn manner leading to cyclopropyl azide 7b. Nmr correlations as well as Hg-H coupling in these systems are discussed.