Synthesis, Reactions, and Rearrangements of 2,4-Diazabicyclo[3.1.0]hexan-3-ones

Ring-opening, cycloaddition and rearrangement reactions of nitrogen-substituted cyclopropane derivatives

“…Thermal isomerisation of a 1,2-diaminocyclopropane derivative into an imidazolin-2-one product under acidic conditions. 58 An interesting, recently reported complementary observation is that the superacid CF 3 SO 3 H (trifluoromethanesulfonic acid; triflic acid) is able to protonate cations such as 6. 59 Dicationic species are thus produced, with ring-opening occurring at the distal cyclopropane C−C bond, which is the regioselectivity expected for cyclopropanes substituted with a σ-withdrawing group.…”

“…Ring-opening isomerisation of donor-acceptor aminocyclopropane derivatives. 164,58 Scheme 57. Rearrangement of a donor-acceptor cyclopropane derived from an indole compound into the anti-inflammatory drug indomethacin.…”

“…58 Another interesting example is the fast thermal isomerisation of the indole-derived acid substrate 89 into the anti-inflammatory drug indomethacin (Scheme 57). 166 Closely related ring-opening reactions of 2,3-methanoindole compounds, occurring…”

“…Formation of N-benzyl pyrrole from a 1,2-diaminocyclopropane derivative. 58 Intermolecular reactions have been comparatively much less studied. An early example involves the unexpected and low yielding ring-opening alkylation of a strained tricyclic substrate with methylmagnesium iodide.…”

“…164 Less reactive molecules, like the imidazolidinone 88, require some activation (Scheme 56, bottom). 58 Various conditions can be applied, including aqueous KOH, in which case the ester is hydrolysed to an acid.…”