Doobary S, Lacey AJD, Sweeting SG, Coppock SB, Caldora HP, Poole DL, Lennox AJJ. Diastereodivergent nucleophile-nucleophile alkene chlorofluorination.
Nat Chem 2024:10.1038/s41557-024-01561-6. [PMID:
38951616 DOI:
10.1038/s41557-024-01561-6]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 05/23/2024] [Indexed: 07/03/2024]
Abstract
The selective hetero-dihalogenation of alkenes provides useful building blocks for a broad range of chemical applications. Unlike homo-dihalogenation, selective hetero-dihalogenation reactions, especially fluorohalogenation, are underdeveloped. Current approaches combine an electrophilic halogen source with a nucleophilic halogen source, which necessarily leads to anti-addition, and regioselectivity has only been achieved using highly activated alkenes. Here we describe an alternative, nucleophile-nucleophile approach that adds chloride and fluoride ions over unactivated alkenes in a highly regio-, chemo- and diastereoselective manner. A curious switch in the reaction mechanism was discovered, which triggers a complete reversal of the diastereoselectivity to promote either anti- or syn-addition. The conditions are demonstrated on an array of pharmaceutically relevant compounds, and detailed mechanistic studies reveal the selectivity and the switch between the syn- and anti-diastereomers are based on different active iodanes and which of the two halides adds first.
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