An Approach for Rapid Increase in Molecular Complexity: Atom Economic Routes to Fused Polycyclic Ring Systems

A protocol
for the asymmetric trimethylenemethane (TMM) [3 + 2]
cycloaddition reaction of alkynyl-substituted TMM donors and unsaturated N-acyl pyrroles employing a chiral bisdiamidophosphite ligand
has been developed. This process generates alkynyl-substituted cyclopentanes
in high yields and diastereo- and enantioselectivities. These chiral
precursors are employed for the atom economic assembly of fused polycyclic
hydrocarbons with hydroindene, hydroazulene, and hydro­cyclo­penta­naph­thalene
scaffolds by consecutive cycloaddition reactions.