Synthesis of 1,4-Diazines by Ring Expansion of 1,3-Diazines

Abstract

Fully saturated piperazin-3-one and quinoxalin-3-one derivatives were prepared by reactions of 2-anilino-2-ethoxy-3-oxothiobutanoic acid anilide with aliphatic 1,2-diamines. An unusual ring expansion of the intermediate 1,3-diazines leads to 1,4-diazines. Moreover, quinoxalin-3-one derivatives from chiral trans-1,2-diaminocyclohexane were obtained with diastereoselectivity >95%.

Synthesis of Saturated Imidazolidin[1,5-a]- and Thiazolidin[3,4-a]perhydroquinoxalin-4-one and Imidazolidin[1,5-a]piperazin-4-one Derivatives. Ring Contraction of Perhydroquinoxalin-4-one to Perhydrobenzimidazolin-2-one

“…14 Studies on the synthesis of fully saturated heterocyclic systems have been our subject of interest. 15,16 In previous work 17 we have described a novel ring expansion of 1,3-diazines to 1,4-diazines resulting in piperazin-3-one and perhydroquinoxalin-3-one derivatives (Scheme 1).…”

Pb(NO3)2 Mediated Synthesis of Pyrazine

“…Due in large part to their similarity with amino acids, piperazinones have proven to be useful tools for drug design and for evaluation interaction between natural ligands and macromolecules. 1 Pyrazines are useful for the treatment of obesity, psychiatric and neurological disorders. 2 Pyrazines are found in such heated foods as bread, different meats, baked potatoes and coffee 3 which are formed from serine and thereonine.…”

One-Pot Synthesis of 3,4-Dihydro-2H-pyrido[1,2-a][1,3,5]triazin-2-one Derivatives fromN-(2′-Pyridinyl)benzoylacetamide and Nitrosobenzenes

“…Products of such type of reaction had proven useful as good building blocks for constructing various heterocyclic systems. 7,8 N-(2¢-Pyridinyl)acetoacetamide (1) furnished the expected product 3a, in contrast to the reaction of N-(2¢-pyridinyl)benzoylacetamide (2) with nitrosobenzenes. This reaction unexpectedly afforded pyrido[1,2-a] [1,3,5]triazin-2-ones 4a-c (Scheme 1).…”

“…This compound has got capacity to react as bielectrophilic system on C-2 in various ways, depending on reagents and reaction conditions, and usually leading to heterocyclic systems by new rearrangements. 7,8 These results encouraged us to undertake a study on the reactivity of N-(2¢-pyridinyl)acetoacetamide (1) and N-(2¢-pyridinyl)benzoylacetamide (2) with nitrosobenzenes. Products of such type of reaction had proven useful as good building blocks for constructing various heterocyclic systems.…”