In the Maillard reaction (non-enzymatic browning), reducing carbohydrates react to 1,2-dicarbonyl compounds that may combine with the epsilon-amino group of lysine to form characteristic pyrrole compounds such as pyrraline and formyline in a Paal-Knorr reaction. In the present study, the Maillard reaction of the rare sugar l-rhamnose was studied. The l-rhamnose-derived dehydration product 3,6-dideoxy-l-mannosone (3,6-DDM) was synthesized and structurally characterized via NMR. Mainly the -pyranose is formed in aqueous solution. 2-(2(S),3(S)-Dihydroxybutyl)quinoxaline was synthesized for the first time and used as a standard for quantification of 3,6-DDM in food. Analysis of 3,6-DDM after conversion to the respective quinoxaline via RP-HPLC-MS/MS revealed concentrations not exceeding 23 mu g/kg in food items such as coffee and brewing malt. Moreover, the Paal-Knorr reaction product of 3,6-DDM with lysine, namely 6-(2-formyl-5-methylpyrrol-1-yl)-l-norleucine (rhamnolysine) was synthesized for the first time by reaction of N--Boc-lysine and 3,6-DDM and purified by semi-preparative ion-exchange chromatography followed by characterization by NMR and HPLC-MS/MS. Rhamnolysine was analysed in 42 food items by RP-HPLC-MS/MS in the MRM mode after enzymatic hydrolysis. The highest concentration of the compound was found in rye bread crust (4.9mg/kg). It appears mainly in foods that are highly heat-treated, roasted or fried.