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Abstract The direct formation of aryl C−O bonds via the intramolecular dehydrogenative coupling of a C−H bond and a pendant alcohol represents a powerful synthetic transformation. Herein, we report a method for intramolecular arene C−H etherification via an umpoled alcohol cyclization mediated by an I(III)N‐HVI reagent. This approach provides access to functionalized chromane scaffolds from primary, secondary and tertiary alcohols via a cascade cyclization‐iodonium salt formation, the latter providing a versatile functional handle for downstream derivatization. Computational studies support initial formation of an umpoled O‐intermediate via I(III) ligand exchange, followed by competitive direct and spirocyclization/1,2‐shift pathways. magnified image
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A Synthesis of Alstonlarsine A via Alstolucines B and F Demonstrates the Chemical Feasibility of a Proposed Biogenesis
Abstract We offer a new biogenetic proposal for the origin of the complex alkaloid alstonlarsine A, through rearrangement of theStrychnosalkaloids alstolucines B and F. Further, we provide evidence of the chemical feasibility of this proposal in the facile conversion of synthetic alstolucines into alstonlarsine A through a short, efficient sequence ofN‐methylation, β‐elimination, and a cascade 1,7‐hydride shift/Mannich cyclization. We believe that this is the first biogenetic proposal involving the “tert‐amino effect”, a hydride‐shift‐based internal redox trigger of a Mannich cyclization. A further interesting feature of the cascade is that its stereochemical outcome most likely originates in conformational preferences during the hydride shift.
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- Award ID(s):
- 2102480
- PAR ID:
- 10391604
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 62
- Issue:
- 4
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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