Abstract
Novel four 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives were formed by reaction of PE and hexose or oligosaccharides including of hexose moiety in soybean lecithin with increase of UV absorption at 350 nm and browning of the solution. Therefore, several pentoses, a heptose and 2-deoxysugars besides hexoses were examined. When any pentose was reacted with PE in DSSL fr. in octane, two 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives without a substitute at 6 position on the aromatic ring were formed with increase of UV absorption at 345nm and browning of the solution. On the other hand, two 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives with 1,2-dihydroxyethyl group at 6 position on the ring were formed when a heptose was reacted with PE in DSSL fr. in octane. Contrary to these results, when 2-deoxysugars, regardless hexose or pentose, were reacted with PE in DSSL fr. in octane, the derivatives were not formed at all and change of UV absorption and browning in the solution could not also be observed. From these results, it is concluded that existence of an oxygen atom on 2 position of sugars is essential to brown, change the UV absorption, and form the pyridinium derivatives by heating and that rearrangement of carbon(s) in the sugar might involve the reaction of PE and sugars to form the pyridinium derivatives.
