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Synthesis of 2H-Chromenes via Hydrazine-Catalyzed Ring-Closing Carbonyl-Olefin Metathesis
preprintsubmitted on 07.08.2019, 13:49 and posted on 08.08.2019, 14:42 by Yunfei Zhang, Janis Jermaks, Samantha N. Macmillan, Tristan Lambert
The catalytic ring-closing carbonyl-olefin metathesis (RCCOM) of O-allylsalicylaldehydes to form 2H-chromenes is described. The method utilizes a [2.2.1]-bicyclic hydrazine catalyst and operates via a [3+2]/retro-[3+2] metathesis manifold. The nature of the allyl substitution pattern was found to be crucial, with sterically demanding groups such as adamantylidene or diethylidene offering optimal outcomes. A survey of substrate scope is shown along with a discussion of mechanism supported by DFT calculations. Steric pressure arising from syn-pentane minimization of the diethylidene moiety is proposed to facilitate cycloreversion.
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in ACS Catalysis
Catalytic Platforms Using Aromatic Ions and Other Charged Species
National Institute of General Medical SciencesFind out more...