Carbamoylierungs‐ und Cyclisierungsreaktionen an N‐Hydroxyisoharnstoffen

Abstract

N-Hydroxyisoharnstoffe 1 nehmen Phenylisocyanat an der HOGruppe auf und bilden die OCarbamoylverbindungen 4. Diese konnen zum A2-1,2,4-0xadiazolin-5-on (Sa), zu 3-Imino-1,2,4-oxadiazolidin-5-onen 5b-5e oder zum A3-l,2,4-0xadiazolin-5-on (9dB) cyclisieren. Die aus Sb-Se hergestellten Hydrochloride 6IAe sind zu den 1,2,4-Oxadiazolidin-3,5-dionen 7b-7e verseifbar. Die IR-und MS-Daten von 4,5,6 und 7 werden diskutiert. Acylalion and Qdization of NHydroxybmrem by Phenyl hcyanateOn adding phenyl isocyanate to the N-hydroxykoureas 1 the 0-carbamoyl derivatives 4 are obtained.They can undergo ring closure to yield A2-1,2,4-oxadiazolin-5-one (Sa), the 3-imino-1,2,4-oxadiazozolidin-5-ones S b S e or A3-1,2,4-oxadiazolin-5-one (9dB). Compounds 5b-Se form the hydrochlorides 6b-6e which can be hydrolized to yield the 1,2,4-oxadiazolidine-3,5-diones 7b-7e. The IR and MS data of compounds 4-7 are discussed.

Synthesis, spectroscopy and structure of CF3CH2OCN, CF3CH2NCO, and (CF3CH2O)2CNHElectronic supplementary information (ESI) available: Experimental and calculated infrared and Raman vibrational frequencies and intensities of CF3CH2OCN, (CF3CH2O)2CNH and CF3CH2NCO. See http://www.rsc.org/suppdata/cp/b2/b212777f/

“…The application of 1 in a nucleophile addition reaction with hydroxylamine or pyrazolidinone derivatives has been reported previously. [10][11][12][13][14][15] Since information is not given in these papers about the synthesis of 1, only a reference to the work of Grigat and Pu ¨tter 4 in one of them, 10 one may surmise that not 1, but 2 has been reacted. We note that a nucleophile substitution reaction between 2 and hydroxylamine or pyrazolidinone derivatives may lead to the same products as the addition of these amines to 1.…”

“…Only six previous papers report the application of 1 in nucleophile addition reactions with hydroxylamine, hydrazine, or pyrazolidinone derivatives. [10][11][12][13][14][15] No information is given in these papers about the synthesis of 1, only a reference to the work of Grigat and Pu ¨tter 4 can be found in one of them. 10 3 has been prepared earlier by reacting 2,2,2-trifluoroethylamine hydrochloride with phosgene 16 and recently by the thermolysis of N,N-diphenyl-N 0 -(2,2,2-trifluoroethyl)urea.…”

Synthesis of 5-Imino-1,2,4-Oxadiazolidin-3-One

“…After the successful synthesis of 3-imino and 5-imino-1,2,4-oxazolidin-5(3)-ones with unsubstituted phenyl group, we undertook the preparation of ortho-substituted phenyl derivatives from the reaction of N-orthosubstituted phenyl-N-carbomethoxycyanamide (2) and N-alkylhydroxylamine. However, in contrast to the N-alkylhydroxylamines, we could only obtain the reaction intermediates of 2-hydroxyguanidine from the reaction of N-aryl-N-carbomethoxycyanamide with hydroxylamine hydrochloride.…”

“…2,: Yield 98%; m.p. 102.5-103 C; 1 H NMR(300 MHz) d 7.30 (br, s, 5H, Ph), 5.80 (br, s, 1H, NH), 3.20 (s, 3H, CH 3 ); IR (KBr) 3232 (NH), 1756 (CO), 1681 (C¼N) cm À1 ; MS m/e (rel.…”