In situ generation of 2,3-allenolates in the coupling of secondary homopropargylic alcohols and aldehydes

A study on a novel oxonia [3,3]-sigmatropic rearrangement as competitive alternative pathway to the acetylenic Prins cyclization on the addition of secondary homopropargylic alcohols to aldehydes catalyzed by iron(III) is described. 'Ab initio' theoretical calculations of the species involved on the rearrangement supports the in situ formation of 2,3-allenolates. The domino process involves three consecutive chemical events in one-pot format reaction (∼70% average).