The chemistry of small ring compounds. Part 27. Heterocyclic condensation products from cyclopropanone and methylamine

The adduct 2 of methylamine with two molecules of cyclopropanone gives, on mild heating, a variety of six- and eight-membered heterocycles (with hetero-atoms NNN, NON, ONO, NONO or ONOO) and three or four unruptured (spiro-)cyclopropyl groups attached to the ring. The cyclisation mechanism involves in all cases an initial rapid dimerisation of 2. The aniline-cyclopropanone adduct 10 on heating gives only the related six-membered cyclo-condensation products.