2513-24-8Relevant 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 (2019/10/08)
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.
An activity scale of cathode materials for the electrochemical cyclisation of allyl 2-bromobenzyl ether
Vanrenterghem, Bart,Breugelmans, Tom
, p. 28 - 36 (2017/03/22)
The electrocatalytic activity of 10 cathode materials (Ag, Au, Cu, Glassy carbon (GC), Ni, Mg, Mn, Pb, Pt and Ti) was examined for the intramolecular cyclisation reaction of allyl 2-bromobenzyl ether to 2-methyl benzopyran. The influence of the cathode materials on the electrocatalytic activity was tested by means of cyclic voltammetry (CV) in an electrolyte solution of allyl 2-bromobenzyl ether (1?mM) + tetrabutylammonium perchlorate (0.1?M) (Bu4NClO4) in methanol (MeOH). On Au, GC, Ni, Mg, Mn, Pb and Pt one single reduction wave was measured while Ag and Cu exhibited two cathodic reduction waves. Ti did not show a voltammetric response. The best electrocatalytic activity was obtained on Ag which showed a shift of the reduction peak potential of 771?mV with respect to GC, the most inert material. In addition to the screening, rotating disk experiments (RDE) in combination with Koutecky Levich analysis and product formation during electrosynthesis were performed. Koutecky Levich analysis of the RDE at peak potential showed that one-electron was transferred at Au, GC, Ni, Mg, Mn, Pb and Pt. On Ag and Cu the number of transferred electrons determined with Koutecky-Levich depends on the potential and can be tuned to specific one- or two-electron transfer. Electrosynthesis showed that on Au, GC, Ni, Mg, Mn, Pb and Pt exclusively 5-methyl benzopyran was formed. On Ag and Cu product formation was depended on the potential and 2-methyl benzopyran and allyl benzyl ether (not cyclized product) were both formed.
Synthesis of benzannulated spiroketals using an oxidative radical cyclization
Sperry, Jonathan,Liu, Yen-Cheng,Wilson, Zoe E.,Hubert, Jonathan G.,Brimble, Margaret A.
scheme or table, p. 1383 - 1398 (2011/06/17)
The synthesis of both mono and bisbenzannulated spiroketals using an oxidative radical cyclization approach is investigated. Although unsuccessful in uncovering a novel route toward bisbenzannulated spiroketals, the oxidative radical cyclization does faci
