Formation of azarhodacyclobutanes with varying N-substitution

• Five new 2-azarhodacyclobutanes have been formed.
• For the first time, isomer selectivity has been observed using TsN3 as the oxidant.
• Boc- and Troc-substituted 2-azarhodacyclobutanes display increased reactivity toward acid.

Oxidation of the rhodium(I) ethylene complex, [(TPA)Rh(η2-CH2CH2)]+ (1, TPA = N,N,N-tris(2-pyridylmethyl)amine) with a selection of nitrene precursors led to formation of N-substituted azarhodacyclobutanes. Appropriate choice of oxidant allowed for selective preparation of one isomer. For example, treatment of 1 with tosyl azide provided isomer 3 exclusively for the first time. Variation of the substituent on the ring-nitrogen was possible e.g., by employing nosyl iodinane precursor 8. Substituted carbamates were also screened, providing two rotamers of isomer type 3. In addition, preliminary reactivity studies revealing the increased chemical reactivity of the product complexes 14 and 15 are presented.

Oxidation of the rhodium ethylene complex, [(TPA)Rh(η2-CH2CH2)]+ (TPA = N,N,N-tris(2-pyridylmethyl)amine) with a selection of nitrene precursors led to formation of 2-azarhodacyclobutanes. Choice of oxidant allowed for selective isomer preparation, including the use of substituted carbamates, which provided two rotamers. Preliminary reactivity studies reveal the increased chemical reactivity of these new complexes.Figure optionsDownload as PowerPoint slide