18385-91-6Relevant academic research and scientific papers
Synthesis of 2 h-chromenes via hydrazine-catalyzed ring-closing carbonyl-olefin metathesis
Jermaks, Janis,Lambert, Tristan H.,Macmillan, Samantha N.,Zhang, Yunfei
, p. 9259 - 9264 (2019)
The catalytic ring-closing carbonyl-olefin metathesis (RCCOM) of O-Allyl salicylaldehydes 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.
