Mendeleev Communications Electronic Version, Issue 1, 1998 (pp. 1–42) Unexpected synthesis of 2-(3-hydroxymethyl-3,3-pentamethyleneacetonyl)- 2-trifluoromethylimidazolidine Vyacheslav Ya. Sosnovskikh* and Michail Yu. Mel’nikov Department of Chemistry, A. M. Gor’ky Urals State University, 620083 Ekaterinburg, Russian Federation. Fax: +7 3432 615 978; e-mail: Vyacheslav.Sosnovskikh@usu.ru The reaction of 2-amino-6-hydroxy-5,5-pentamethylene-1,1,1-trifluoro-2-hexen-4-one with ethylenediamine, in contrast to the similar reaction involving 2-amino-6-hydroxy-5,5-dimethyl-1,1,1-trifluoro-2-hexen-4-one, leads to 2-(3-hydroxymethyl-3,3-pentamethyleneacetonyl)- 2-trifluoromethylimidazolidine.It is known1 that ethylenediamine reacts with b-amino-b-polyfluoroalkylvinylketones at two electrophilic centres simultaneously to produce 2,3-dihydro-1,4-diazepines. In an attempt to synthesize diazepines containing such substituents as the trifluoromethyl and hydroxyalkyl groups, we found that 2-amino-6-hydroxy-5,5-dimethyl(pentamethylene)-1,1,1-trifluoro- 2-hexen-4-ones 1,2, obtained by the condensation of 4-hydroxy- 3,3-dimethyl(pentamethylene)butan-2-ones with trifluoroacetonitrile, 2 react with ethylenediamine in quite different ways although their structures are very similar.For instance, aminoenone 1 gives the expected diazepine 3 in a 75% yield, while aminoenone 2 gives imidazolidine 4 in the same yield under these conditions.† In the latter case, double nucleophilic attack at the b-carbon atom with elimination of an ammonia molecule takes place, while the carbonyl group is retained, most likely due to steric factors.The formation of 2-trifluoromethyl-2-ethoxycarbonylmethylimidazolidine from the reaction of ethylenediamine with ethyl trifluoroacetoacetate has been reported previously,3 but the † 2,3-Dihydro-5-trifluoromethyl-7-(2-hydroxy-1,1-dimethylethyl)-1,4-diazepine 3. Aminoenone 1 (300 mg, 1.4 mmol) was dissolved in 400 ml (360 mg, 6.0 mmol) of ethylenediamine, and the reaction mixture was kept for three days at room temperature.The resulting crystals of diazepine 3 were recrystallised from hexane, yield 250 mg (75%), mp 130–131 °C. Found (%): C 50.87, H 6.53, N 11.73. Calc. for C10H15F3N2O (%): C 50.84; H 6.40; N 11.86. IR (vaseline oil, n/cm–1): 3345, 3140 (NH, OH), 1620, 1570, 1550 (C=N, C=C, NH). 1H NMR (80 MHz, CDCl3) d: 1.19 (s, 6H, 2CH3), 2.9 (br. s, 2H, OH, NH), 3.50 (br. s, 2H, CH2N), 3.57 (s, 2H, CH2O), 3.78 (t, 2H, CH2N=), 5.07 (s, 1H, =CH). 2-(3-Hydroxymethyl-3,3-pentamethyleneacetonyl)-2-trifluoromethylimidazolidine 4 was obtained from 200 mg of aminoenone 2 under the same conditions as diazepine 3. Yield 180 mg (76%), mp 85–86 °C (hexane).Found (%): C 53.26; H 7.32; N 9.59. Calc. for C13H21F3N2O2 (%): C 53.05; H 7.19; N 9.52. IR (vaseline oil, n/cm–1): 3360 , 3315, 3195 (NH, OH), 1705 (C=O), 1645 (NH). 1H NMR (80 MHz, CDCl3) d: 1.2–2.0 [m, 10 H, (CH2)5], 2.90 (s, 2H, CH2), 3.02 (s, 4H, CH2CH2), 3.4 (br. s, 3H, OH, 2NH), 3.72 (s, 2H, CH2O). literature contains no data regarding this reaction pathway involving b-amino-b-polyfluoroalkylvinylketones.At present, we are trying to clarify whether the formation of imidazolidine 4 revealed here is a characteristic property of b-amino-b-polyfluoroalkylvinylketones or if this reaction presents a specific case caused by the structural features of aminoenone 2. This work was supported by the Russian Foundation for Basic Research (grant no. 96-03-33373). References 1 K. I. Pashkevich, A. Ya. Aizikovich and I. Ya. Postovskii, Izv. Akad. Nauk SSSR, Ser. Khim., 1981, 455 (Bull. Acad. Sci. USSR, Div. Chem. Sci., 1981, 30, 420). 2 V. Ya. Sosnovskikh and M. Yu. Mel’nikov, Zh. Org. Khim., 1998, in press. 3 G. M. J. Slusarczuk and M. M. Joullie, J. Org. Chem., 1971, 36, 37. OH O NH2 CF3 R1 R2 + (CH2NH2)2 –NH3 –H2O –NH3 OH N CF3 NH Me Me OH O HN NH CF3 1,2 3 4 1 R1 = R2 = Me 2 R1 + R2 = (CH2)5 Received: Moscow, 3rd October 1997 Cambridge, 28th November 1997; Com. 7/07584G