132723-22-9

Upstream product

• 28637-56-1 2,2-dimethyl-5,6,7,8-tetrahydro-4H-benzo[d][1,3]dioxin-4-one 
• 1655-07-8 ethyl 2-oxocyclohexane carboxylate 
• 18709-01-8 2-hydroxycyclohex-1-enecarboxylic acid 

Downstream Products

• 51089-06-6 2-oxo-N-phenylcyclohexane-1-carboxamide 
• 18709-01-8 cyclohexanone-2-carboxylic acid 
• 18705-27-6 oxocyclohexane-2-carboxylate 

Relevant academic research and scientific papers

Periselectivity in the aza-Diels-Alder Cycloaddition between α-Oxoketenes and N-(5-Pyrazolyl)imines: A Combined Experimental and Theoretical Study

The thermal 6πaza-Diels-Alder cycloadditions between α-oxoketenes, in situ derived from a thermally induced Wolff rearrangement of 2-diazo-1,3-diketones, and N-(5-pyrazolyl)imines as prototypical electron-rich 2-azadienes lead to two distinct sets of products, essentially as a function of the nature of the α-oxoketenes involved. For instance, cyclic five-membered α-oxoketenes lead preferentially to spiro hydropyridin-4-ones, which involves the α-oxoketenes as the 2πpartners at their Ca? C double bond and the N-(5-pyrazolyl)imines as the 4πpartners at their 2-azadiene moiety. In contrast, other cyclic and acyclic α-oxoketenes lead preferentially to 1,3-oxazin-4-ones, which now involves the α-oxoketenes as the 4πpartners at their 1-oxadiene moiety and the N-(5-pyrazolyl)imines as the 2πpartners at their Ca? N double bond. A computational modeling study using DFT methods allowed rationalizing this change of periselectivity: the formation of spiro hydropyridin-4-ones is under thermodynamic control while the formation of 1,3-oxazin-4-ones is kinetically controlled, and slightly thermodynamically disfavored in the five-membered ring series. The competing cyclodimerization of the α-oxoketenes is also studied in detail.

Direct Observation of α-Oxo Ketenes Formed from 1,3-Dioxin-4-ones and the Enols of β-Keto Esters

The enol forms of β-keto esters thermolyze to alcohols and α-oxo ketenes, which are characterized by low-temperature IR spectroscopy and on warming regenerate the β-hydroxy-α,β-unsaturated esters. The matrix isolated s-Z and s-E forms of α-oxo ketenes are characterized and photochemically converted into other conformers or sites.Matrix photolysis of 2,2,6-trimethyl-1,3-dioxin-4-one gives the s-Z acetylketene initially. α-Oxo ketenes polymerize in the cold and dimerize only at elevated temperatures.

The 2-oxocyclohexanecarboxylic acid keto-enol system in aqueous solution

Flash photolysis of 2-diazocycloheptane-1,3-dione or 2,2-dimethyl-5,6,7,8-tetrahydrobenzo-4H-1,3-dioxin-4-one in aqueous solution produced 2-oxocyclohexylideneketene, which underwent hydration to the enol of 2-oxocyclohexanecarboxylic acid, and the enol then isomerized to the keto form of the acid. Isomerization of the enol to keto forms was also observed using solid enol, a substance heretofore commonly believed to be the keto acid. Rates of ketonization were measured in perchloric acid, sodium hydroxide, and buffer solutions, and a ketonization rate profile was constructed. Rates of enolization of the keto acid were also measured using bromine to scavenge the enol as it formed. Rates of enolization and ketonization were then combined to provide the keto - enol equilibrium constant pKE = 1.27. This and some of the other results obtained are different from the corresponding quantities for the 2-oxocyclopentanecarboxylic acid keto - enol system. These differences are discussed.

Synthesis of β-Ketocarboxamide Derivatives Using 2,2-Dimethyl-2H,4H-1,3-dioxin-4-ones

Thermal reaction of 2,2-dimethyl-2H,4H-1,3-dioxin-4-ones (1) with amines was studied.Acylketenes 2, generated by heating of 1, reacted with anilines and benzylamine to give the corresponding β-ketocarboxamides (3,4, and 5) in good yields.The reaction of 1 with ammonia gave 3-amino-2-alkenamides (7), which were hydrolyzed to β-ketocarboxamides (6).The former products 7 were readily transformed to the 6-substituted 2-methyl-3H-pyrimidin-4-ones (9) via the 3-acetamido-2-alkenamides (8).Acylation of O-benzylhydroxylamine with 1 gave the β-ketohydroxamic acids 10.Debenzylation of 10 followed by cyclization gave rise to 5-alkyl-3-hydroxyisoxazoles (12).The reaction of 1 with amides gave the corresponding N-acetylated amides (13). Keywords --- 2H,4H-1,3-dioxin-4-one; thermal fragmentation; acylketene; acylation; carboxamide; hydroxamic acid; 3-hydroxyisoxazole; 3H-pyrimidin-4-one