Metal- and Solvent-free Synthesis of Functionalized Dihydrooxa­zolo[3,2-a]indoles by One-Pot Tandem Assembly of 3H-Indoles and Propargylic Alcohols

The reaction of 3 H -indoles with tertiary propargylic alcohols to give functionalized dihydrooxazolo[3,2- a ]indoles in good to excellent yields has been developed. This metal- and solvent-free, one-pot tandem assembly proceeds under mild conditions (22–60 °C) and is regio- and stereoselective: either the Z - or E -isomers (relative to the double bond) are alternatively formed depending on other functionalized substituents on the propargylic alcohols.