Dimethyl reaction with diketene

On the other hand y-pyrones or 1,3-diketones could be obtained from the reactions of ketone derived enamines with diketene 423-426). The addition of dimethyl ketene dimer to aldehyde or ketone derived enamines produced cyclohexanediones 425,426). 

Pyrimido[l,2-a][l,3,5]triazine derivatives (100) were obtained by the condensation of the corresponding diaminotriazines (99) with diethyl malonate (Equation (20)) <75GEP2450119>. The reactions of 3-amino-5,6-dimethyl-[l,2,4]triazine (101) with diketene gave substituted pyrimido[l,2-( ][l,2,4]triazine (38) (Equation (21)) <84H(22)1095>. 

Preparative Method by the reaction of 2,4-dimethyl-3-pentanol with diketene followed by methylation and deacylative diazo transfer. ... 

Pyrans and related compounds react with ammonia to give pyridines. A commercially useful example is the reaction of dehydroacetic acid (derived from diketene) with ammonia to give 2,6-dimethyl-4-pyridinone [7516-31 -6] via 2,6-dimethyl-4-pyridinone-3-carboxyhc acid [52403-25-5]. Chlorination of the pyridone gives clopidol [2971-90-6] (56), a coccidiostat (72,73). 

Reaction of 272 with acrylic acid, /9-chlorobutyric acid, /9-diketones, or a,/9-unsaturated ketones gave the expected diazepines, while acetoacetic ester and diketene reacted only at the primary amino group.323 Similarly, 273 was obtained from acetylacetone and 2,3-dimethyl - 7- aminoindole.32 4... 

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