Water--more than just a green solvent: a stereoselective one-pot access to all-chiral tetrahydronaphthalenes in aqueous media.

A facile and highly stereoselective construction of heavily functionalized chiral tetrahydronaphthalene skeletons fused with an oxazolidine moiety has been developed. The process involves an organocatalytic tandem Michael/nitrone formation/intramolecular [3+2] nitrone-olefin cycloaddition in aqueous media. Using rationally designed substrates, the reaction conditions have been optimized and the one-pot process has been applied to a series of nitroolefin acrylates and aldehydes. The N-hydroxyphenylamine component used in the second step has also been varied. The stereochemistry of one product has been verified by an X-ray crystal structure determination. The water used in the strategy not only constitutes an environmentally benign solvent, but also helps to improve the reactivity and stereoselectivity.