Uses
5,6-Dimethyl-2,3-dihydropyrazine can be used in studies of perfume composition comprising fragrance modulator compounds and silicic acid esters for increasing and prolonging the intensity of fragrance.
Synthesis
Over a period of 2 hours, 2,3-butanedione (18.6 g, 216 mmol, dissolved in 200 mL of anhydrous ether) was added slowly and dropwise to a solution of ethylenediamine (13 g, 216 mmol) in anhydrous ether (600 mL). The reaction mixture was stirred continuously for 3 hours at room temperature. Subsequently, the clarified reaction solution was concentrated under reduced pressure to give a brown oily crude product. Purification of the crude product by reduced pressure distillation resulted in 16.6 g (70% yield) of the target compound 5,6-dimethyl-2,3-dihydropyrazine (Formula F) as a clarified yellow oil. The boiling point was 60 °C/16 mm Hg. Nuclear magnetic resonance hydrogen spectroscopy (NMR, CD3) data were as follows: δ 3.3 (broad single peak, 4H), 2.1 (single peak, 6H) ppm.
References
[1] Transition Metal Chemistry, 2013, vol. 38, # 1, p. 31 - 36
[2] Chemical and Pharmaceutical Bulletin, 2010, vol. 58, # 6, p. 825 - 828
[3] Patent: WO2005/79769, 2005, A2. Location in patent: Page/Page column 91
[4] Synthesis (Germany), 2013, vol. 45, # 11, p. 1546 - 1552
[5] Patent: EP1254899, 2002, A2. Location in patent: Page 46
