Reactions of Alloxan and Alloxantine. Structure of Alloxantine and Hydrindantine

The Strecker Degradation of α-Amino Acids.

“…Utilization of the degrading power of ketones in the elucidation of structure Since so many facts have been collected in connection with the degrading power of ketones, it seems possible to use the results gained, especially the -CO(C-C)"CO-( = zero or an integer) "rule," as a tool in the elucidation of the constitution of carbonyl compounds. Alloxantin (XV) does not contain this "group"; nevertheless it is an active agent in the Strecker degradation (31). This is due to the fact that in warm solution it decomposes with the formation of alloxan (XVI), the latter being an active agent.…”

Reversible Cross-Linking and De-Cross-Linking System of Polystyrenes Bearing the Monohydrate Structure of Vicinal Tricarbonyl Group through Water–Alcohol Exchange Reactions at Ambient Conditions

“…Vicinal tricarbonyl compounds, such as alloxan, 1,2,3-indanetrione, dehydroascorbic acid, and diphenylpropanetrione (DPPT, 1 ), have by definition the three contiguous carbonyl groups, and are characterized by a highly electrophilic central carbonyl group, which is activated by the adjacent two carbonyls and significantly reactive toward various nucleophiles, such as water and alcohols (Scheme ). , Hence, vicinal tricarbonyl compounds are usually obtained as their hydrated forms (2,2- gem -diol, DPPT-H 2 O, 2 ) as a result of hydration with moisture in air or solvents used during the isolation processes (Scheme a). These hydrates can be dehydrated to give pure free vicinal tricarbonyls ( 1 ) by heating under vacuum, − sublimation, , distillation, − crystallization, azeotropic removal of water, and utilization of dehydrating agents such as molecular sieves 4A or P 2 O 5 . ,, This reversible hydration-dehydration nature of vicinal tricarbonyls enables us to utilize them as recyclable dehydrating agents . Of particular interest is that the reversible hydration process is accompanied by disappearance and appearance of the distinctive yellow color due to the collapse and recovery of the contiguous three carbonyl groups, respectively, hence being detectable by the naked eye. , The vicinal tricarbonyl compounds exhibit a similar behavior toward alcohols (Scheme b); the addition of alcohols readily proceeds at ambient temperature to form the corresponding alcohol adducts (hemiketal, DPPT-ROH, 3 ) without any catalyst, being accompanied by disappearance of their distinctive color arising from the vicinal tricarbonyl structures.…”

“…Motivated by the characteristic features of vicinal tricarbonyl compounds, we recently reported design and synthesis of a polystyrene derivative bearing acyclic vicinal tricarbonyl structures in the side chains (4) and detailed investigation of its reversible addition−elimination behavior of water and alcohols to the vicinal tricarbonyl polymer (Scheme 1c). 13−16 The vicinal tricarbonyl pendants of 4 readily reacted with water or alcohols to quantitatively yield the corresponding water or alcohol adduct polymer 5.…”

Construction of reversible hydration–dehydration system by a model compound and a novel polymer bearing vicinal tricarbonyl structure

“…[2][3][4][5] Generally, vicinal tricarbonyl compounds are obtained as their hydrate-form (2,2-geminal diol), because their highly electrophilic nature causes their rapid reactions with moisture in solvents or water used during the isolation processes. [6][7][8][9] These hydrates can be dehydrated by drying them under vacuum, 6,[9][10][11][12][13][14][15] by utilization of dehydrating agents, 8,10,13,14,16,17 by azeotropic removal of water, 16 and by distillation under vacuum 18,19 to afford the pure tricarbonyl forms. These hydration-dehydration behaviors of tricarbonyl compounds imply their reversible nature, and thus they are regarded as organic dehydrating agents that can be recycled and used repeatedly.…”