83124-80-5Relevant articles and documents
Trihaloacetylated enol ethers - General synthetic procedure and heterocyclic ring closure reactions with hydroxylamine
Colla,Martins,Clar,Krimmer,Fischer
, p. 483 - 486 (2007/10/02)
An improved procedure is described for preparing β-trichloro- and β-trifluoroacetyl derivatives of six simple enol ethers, in analytically pure form, high yield, and on an up to molar scale. The 4-alkoxy-1,1,1-trichloro[fluoro]-3-alken-2-ones 4a-c and 5a-c, thus obtained, are cyclocondensed with hydroxylamine hydrochloride (in pyridine, 35°C) to afford the 5-hydroxy-5-trichloro[fluoro]methyl-4,5-dihydroisoxazoles 6 and 7 in high yield. With cyclic substrates, i.e. the trihaloacetyl dihydrofurans and -2H-pyrans 4d, e and 5d, e, a competitive rearrangement reaction gives 3-cyano-2-hydroxy-2-trichloro[fluoro]methyltetrahydrofurans and -2H-pyrans 8 and 9, respectively. Direct condensation to a dihydroisoxazole prevails at 0°C (>85% for 4d, 5d), rearrangement to the cyano compounds at higher temperatures (65-70°C, > 70%). Under either condition, the respective heterocycle may be isolated in > 60% yield (except for 6e).
Enol Ethers, VIII. Acylation of Enol Ethers with Reactive Carbonyl Chlorides
Effenberger, Franz,Maier, Roland,Schoenwaelder, Karl-Heinz,Ziegler, Thomas
, p. 2766 - 2782 (2007/10/02)
Enol ethers 2 are acylated under mild conditions with activated acyl chlorides, e. g. chloroacetyl chlorides 1a, b, cyanoacetyl chloride (6c), and malonic acid chlorides 6a, b in good yields.The products formed and the yield depend on the acylation potential of the acyl chlorides.The potential β-keto aldehydes 4, 5, and 1,3,5-tricarbonyl compounds 8 obtained are valuable intermediates for heterocyclic synthesis.
