18521-11-4Relevant academic research and scientific papers
Synthesis of α,β-Epoxyacyl Azides and Their Rearrangement to Epoxy Isocyanates and 3- and 4-Oxazolin-2-ones
Lemmens, Jacques M.,Blommerde, Willem W. J. M.,Thijs, Lambertus,Zwanenburg, Binne
, p. 2231 - 2235 (2007/10/02)
The conversion of α,β-epoxy carboxylates 6 into α,β-epoxyacyl azides 4 proceeds either via reaction of the mixed anhydrides 7 with sodium azide or via reaction of epoxyacyl chlorides 8 with hydrazoic acid-pyridine.The latter method is preferred.The azides 4 undergo a smooth thermal Curtius rearrangement to give 4-oxazolin-2-ones 10 for the substrates 4a-h having a hydrogen atom at C(β).Monitoring this reaction by means of IR shows that the epoxy isocyanates 5 are intermediates.Intramolecular ring expansion of 5 then leads to 3-oxazolin-2-ones 9 that tautomerizeto the 4-isomers 10a-h.Epoxyacyl azides 4i,n-q, having no hydrogen atom at C(β), producing 3-oxazolin-2-ones 9i,n-q by a proton shift is not possible.The products 9i and 9q rapidly add water at the imine bond to give oxazolidin-2-ones 11.Epoxy isocyanate 5k is reasonable stable in solution; reaction with methanol affords urethane 12.
SYNTHESIS OF α,β-EPOXY DIAZOMETHYL KETONES
Thijs, L.,Smeets, F. L. M.,Cillissen, P. J. M.,Harmsen, J.,Zwanenburg, B.
, p. 2141 - 2144 (2007/10/02)
The preparation of eighteen epoxy diazomethyl ketones 1 is described.Two general methods were developed.Firstly, treatment of the mixed anhydrides of glycidic acids and carbonic acid ester with diazomethane led to the title compounds in yields ranging from 17-74 percent.Secondly, glycidyl chlorides which were obtained from sodium glycidates and oxalyl chloride, gave the desired products upon treatment with diazomethane ( yields 60-74 percent).The required α,β-epoxy carboxylic esters were prepared by Darzens condensation and epoxidation of α,β-unsaturated esters, but in some cases also by reaction of α-oxo carboxylic esters with diazomethane.
