Construction of Spiro[4.5]decanes via Annulations of Azadienes with Nazarov Reagent and DFT Studies

A NaH-promoted domino reaction between azadiene bearing an indene moiety with Nazarov reagent was developed. A variety of spiro[4.5]decane derivatives were obtained via [4+2] cycloaddition with good yields and high diastereoselectivity. The domino strategy benefited from mild reaction conditions and very broad substrate scope. Furthermore, a gram-scale experiment and a transformation of the product were carried out. Lastly, density functional theory (DFT) calculations have been performed to verify the proposed reaction mechanism and analyze the observed diastereoselectivity.