Organocatalytic Asymmetric Synthesis of 3‑Chlorooxindoles Bearing Adjacent Quaternary–Tertiary Centers
2016-02-20T11:06:01Z (GMT) by
A new methodology was developed for the synthesis of enantiomerically enriched 3,3-disubstituted 3-chlorooxindoles <b>3</b> via a Michael addition of 3-chloroxindoles to nitroolefins <b>2</b>, catalyzed by chiral squaramide <b>10</b>. Products with adjacent quaternary–tertiary centers were isolated in excellent yields (up to 99%), high diastereoselectivities (up to 11:1), and enantiomeric purities (up to 92%). This is the first example where 3-chloroxoindoles <b>1</b> have been used as nucleophiles in a highly stereoselective organocatalytic reaction.