Diels–Alder dimerization of ene-allenes and enyne-allenes generated via the propargylic Alder–ene reaction of diynes and triynes

Abstract

Efficient Diels–Alder dimerizations of ene-allenes and enyne-allenes to generate highly functionalized spirocycles and the DFT studies of their exo/endo mode and stereoselectivity are described. The ene-allenes and enyne-allenes are generated in situ via the propargylic Alder–ene reaction of alkyne ene-donors tethered to ene-acceptor alkynes or 1,3-diynes. The chemo-, regio-, and stereo-selectivities of the dimerization depend on the tether structure and the substituents on the ene-donors and acceptors, while the solvent plays a crucial role in the [1,5]-H shift of the dimers.