Pyrroline, 2-propionyl

MnOg added in small portions with shaking to a soln. of 2,2-dimethyl-l-hydroxy-5-(l-nitropropyl)pyrrolidine in petroleum ether (b. p. 40-60°), and the product isolated after 4 hrs. shaking 5,5-dimethyl-2-propionyl-Zl -pyrroline N-oxide. Y 55%. F. e., also with 2,3-dichloro-5,6-dicyanoquinone, s. W. D. S. Bowering et al., A. 669, 106 (1963). 

T Hofmann, P Schieberle. Flavor contribution and formation of the intense roast-smelling odorants 2-propionyl-l-pyrroline and 2-propionyltetrahydro-P5Tidine in Maillard-type reactions. J Agric Food Chem 46 2721-2726, 1998. 

The principal impact aroma compounds of freshly prepared popcorn were determined by Schieberle as 2-acetyltetrahydropyridine, 2-acetyl-1-pyrroline, and 2-propionyl-1-pyrroline (49). The crackerlike aroma of the tetrahydropyri-dine, which exists in two tautomeric forms (2-acetyl-1,4,5,6- and 2-acetyl-3,4,5,6-tetrahydropyridine) was previously identified as the character compound of Saltine crackers (50). The decrease of these compounds during storage was directly correlated with staling flavor. Another popcornlike odor note, 2-acetyl-... 

PGA-mediated deprotections of l-[iV-(phenylacetyl)amino]-4,5-dioxohexane and 1-[A -(phenylacetyl)amino]-4,5-dioxoheptane were used as the key steps in the synthesis (Fig. 5) of the strong natural roast odorants 2-acetyl-1-pyrroline and 2-propionyl-l-pyrroline [13]. 

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