Also discussed are the reactions of cascade cyclizations, heterocyclization involving enyne-carbodiimides, and new achievements in some classical cycloaddition reactions, such as the Diels-Alder condensation with acetylenic dienophiles, [2+2] cycloadditions with an acetylene component leading to the creation of a cyclobutene
ring, and new results in cyclobutene
syntheses by [2+2] acyclization of phosphorus containing 1,3-butadiene derivatives synthesized starting with propargyl-type alcohols.
The main components of the Lippia sidoides Cham, essential oil used in the present study were: cycloheptatriene, benzene, methyl-toluene, cyclobutene
, carvacrol and thymol.
In order to study the effect of unsaturation on the ring strain in small cyclic molecules, the conventional strain energies for cyclobutene
, azetidine-1-ene, phosphetane-1-ene, azetidine-2-ene, and phosphetane-2-ene are determined within the isodesmic, homodesmotic, and hyperhomodesmotic models.
Other copolymers such as those with cyclobutene
and cyclopentene are being developed.