The asymmetric total synthesis of clovan-2,9-dione with a [6.3.1.0]dodecane skeleton has been achieved. The synthesis features a Rh(I)-catalyzed [3 + 2 + 1] cycloaddition of 1-yne-vinylcyclopropane (1-yne-VCP) with CO and an intramolecular aldol reaction to obtain the skeleton of the target molecule.

A concise total synthesis of mesembrine (four steps from known compound) was achieved both racemically and asymmetrically. Two key reactions were used here. One is the Rh(I)-catalyzed [5 + 1] cycloaddition of vinylcyclopropane 3c and CO. The other one is Buchwald's Pd-catalyzed coupling reaction that coupled β,γ-cyclohexenone 2c with aryl bromide 5 (using dppe ligand for racemic or (S)-Antphos ligand for asymmetric synthesis) to give γ,γ-disubstituted α,β-cyclohexenone 1c. Finally, aza-Michael addition converted 1c to mesembrine.

A metal-free, TfOH (1.1 equiv)-mediated formal cycloisomerization of easily prepared allene-alkynylbenzenes to give pyrrolidines and cyclopentanes derivatives was developed. This reaction is initiated by the generation of allylic cation from allene, followed by alkyne's reaction with the allylic cation, to give a vinyl cation, which is finally intercepted by the triflate (TfO) anion. This cycloisomerization can be further tuned to become an acid-mediated intramolecular formal [4+3] cycloaddition by using 10 equiv of TfOH (The excess acid was used to promote the Friedel-Crafts reaction of the acid-mediated cycloisomerization products). The present system can also be applied to synthesized F-incorporated products by using HBF or MeOBF as the fluoro source.