Rapid Asymmetric Synthesis of Highly Functionalized Indanols via a Michael/Henry Organocascade with Submol% Squaramide Catalyst Loadings

An expedient asymmetric synthesis of polyfunctionalized indanols bearing four contiguous stereogenic centres, including a quarternary centre through the use of sub-mol% amounts of a squaramide catalyst within minutes is presented. A gramscale experiment of this Michael/Henry organcascade pushes the frontier of catalyst loading of organocascades down to only 0.1 mol%, attaining a TON of up to 910.