Reaction of Alkenylfurans with Ethyl Diazoacetate

✍ Scribed by Prof. Dr. Oleg M. Nefedov; Dr. Viacheslav M. Shostakovsky; Dipl.-Chem. Alexander E. Vasilvizky

• Publisher: John Wiley and Sons
• Year: 1977
• Tongue: English
• Weight: 233 KB
• Volume: 16
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.197706462

✦ Synopsis

Synthesis of a Stable 1,3,4-Dioxazolidine[**]

By Jurgen Varwig and Rudiger Mews"] Whereas 1,3,2-['] and 1,2,4-dio~azolidines~~~, compounds ( 1 ) and ( ) respectively, are well documented, to our knowledge only the thermally unstable 1:i:l adduct of tert-butyl isocyanide, 2-methyl-2-nitrosopropane and phenyl isocyanate has so far been assigned the 1,3,4-dioxazolidine structure (3)purely on the basis of its mass

We have now been able to synthesize ) in 25 % yield from bis(trifluoromethy1)diazomethane and trifluoronitrosomethane: 110 "C 2 C F a O + 3 (CF3)zCNz ------+ F3C. CF3 (30) Apparently hexafluoroacetone is formed as intermediate product in this reaction, the yield of (3 a) being almost doubled due to reaction according to eq. (b): CFSNO + (CF3)2CN2 + (CF&CO -+ (3a) + Nz (b) The product ( 3 a ) is a water-clear liquid, b. p. 85 "C. The new compound is extraordinarily stable, both thermally and chemically; concentrated alkalis and acids decompose it only slowly. (3 a) was characterized by elemental analysis and by IR and mass spectra; "F-and 13C-NMR spectra afforded proof of its s t r u ~t u r e ~~] . The "F-NMR spectrum shows three signals in the intensity ratio 2:2: 1 [6(2,5-CF$)= -73.37, mult.; 6(2,5-CF:)= -76.70, sept., JP(A)~(~)=4.2 Hz; S(NCF,)= -64.58, sept., J ~~( ~) = 9 . 1 8 Hz], which do not permit unequivocal differentiation between (3 a ) and its 1,3,2-isomer ( 1 a), since similar intensity and coupling ratios are expected for ( 1 a ) for hindered inversion at nitrogen15]. The 3C-NMR spectrum, however, shows two nonequivalent quarternary carbon atoms