Kennedy CR, Choi BY, Reeves MGR, Jacobsen EN. Enantioselective Catalysis of an Anionic Oxy-Cope Rearrangement Enabled by Synergistic Ion Binding.
Isr J Chem 2020;
60:461-474. [PMID:
33132416 PMCID:
PMC7592710 DOI:
10.1002/ijch.201900168]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 02/20/2020] [Indexed: 01/09/2023]
Abstract
Charge-accelerated rearrangements present interesting challenges to enantioselective catalysis, due in large part to the competing requirements for maximizing reactivity (ion-pair separation) and stereochemical communication. Herein, we describe application of a synergistic ion-binding strategy to catalyze the anionic oxy-Cope rearrangement of a symmetric bis-styrenyl allyl alcohol in up to 75:25 e.r. Structure-reactivity-selectivity relationship studies, including linear free-energy-relationship analyses, with bifunctional urea catalysts indicate that H-bonding and cation-binding interactions act cooperatively to promote the chemo- and enantioselective [3,3]-rearrangement. Implications for catalyst designs applicable to other transformations involving oxyanionic intermediates are discussed.
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