Reissert compound studies. XL. The first monocyclic reissert compounds

Abstract

Pyridazine and pyrimidine have been reacted with trimethylsilyl cyanide and benzoyl chloride to give the first examples of Reissert compounds derived from monocyclic systems.

Synthesis and structural study of a new series of 2‐methylsulfanyl‐tetrahydropyrimidines from β‐alkoxyvinyl trihalomethyl ketones

“…Strategies that have been developed to obtain the tetrahydropyrimidine ring include: i) dialkylation of both nitrogen atoms of the pyrimidine ring [1] or one of the backbone carbons [2], ii) reduction of the parent pyrimidine [3], iii) condensation of 1,5-diamines with cyanogen bromide or aldehydes [4][5][6][7], iv) reaction of , -unsaturated carbonyl compounds or acrylates with dinucleophiles of the N-C-N type [8][9][10][11][12], and v) addition reactions to pyrimidines [13][14][15]. An interesting method, based on a triad of reaction components such as 3-oxo esters, 1,3-diketones or -alkoxyvinyl trichloromethyl ketones with benzaldehyde and (thio)urea, resulting in the formation of a series of 4-fluoroalkyl [16] and 4-trichloromethyl [17] substituted tetrahydropyrimidines, has been reported.…”

An expedient and new synthesis of pyrrolo[1,2-b]pyridazine derivatives

“…The first involves condensation reactions, such as the condensation of oxazolo[3,2- b ]pyridazinium perchlorates with malononitrile, ethyl cyanoacetate and ethyl malonate in the presence of sodium ethoxide [ 15 ]; the condensation of 1,4,7-triketones with hydrazine followed by dehydrogenation [ 16 ]; the condensation of cyanoacetic acid hydrazide with 3-bromo-1,1,3-tricyano-2-phenylpropene [ 17 ]; and the reaction between 3-chloropyridazines with propargylic alcohol in the presence of Pd(PPh 3 ) 2 Cl 2 –CuI with diethylamine as the reaction medium [ 18 – 19 ]. The second approach is based on cycloaddition reactions, such as the cycloaddition of dimethyl acetylenedicarboxylate to the Reissert compound of pyridazine [ 20 ], the 1,3-dipolar cycloaddition of pyridazinium dichloromethylide generated by the carbene method [ 21 ], and the cycloaddition of alkylidene cyclopropane derivatives to pyridazine in the presence of Pd(PPh 3 ) 4 [ 22 ].…”

A Novel Approach for the Synthesis of Highly Fluorescent Pyrrolo[1,2-b]pyridazines

“…The first comprises condensation reactions, such as the condensation of oxazolo [3,2b]pyridazinium perchlorates with malonitrile, ethyl cyano acetate and ethyl malonate in the presence of sodium ethoxide, 13 the condensation of 1,4,7-triketones with hydrazine followed by dehydrogenation, 14 the condensation of cyanacetic acid hydrazide with 3-bromo-1,1,3-tricyano-2-phenylpropene, 15 and the reaction between 3-chloropyridazines with propargylic alcohol in the presence of a Pd(PPh 3 ) 2 Cl 2 -CuI with diethylamine as the reaction medium. 16 The second path is based on cycloaddition reactions, such as the cycloaddition of dimethyl acetylenedicarboxylate to the Reissert compound of pyridazine, 17 the 1,3-dipolar cycloaddition of pyridazinium dichloromethylide generated by the carbene method, 18 and the cycloaddition of alkylidene cyclopropane derivatives to pyridazine in the presence of Pd(PPh 3 ) 4 . 19 Unsubstituted pyrrolo [1,2-b]pyridazine 1 was obtained by Flitsch and Kramer (Figure 1).…”