Highly soluble annelated bi-and terpyridines were prepared α,β-unsaturated ketone and the cyclization of the resulting 1,5-diketone in the presence of ammonium acetate. in 46-60% yields by a two-step procedure which combines the Michael addition of an enolizable cyclic ketone with an Annelated polypyridines constitute a class of compounds by aldol condensation/dehydration of octahydroacridone with 4-substituted benzaldehydes. However, with aliphatic that are effective for the complexation of metals and organic guests in their preorganized clefts and cavities. [1] In aldehydes this procedure did not lead to the desired α,βunsaturated ketones due to their facile enolization. An order to use these structures in molecular recognition there is a strong need to develop an efficient approach for the alternative strategy for the preparation of substituted annelated pyridines, employing ternary iminium salts as synthetic synthesis of derivatives which are soluble in common organic solvents. However, since the initial work of Bell [2] equivalents for aliphatic and aromatic aldehydes, has been reported by Risch et al. [3eϪ3g] In this case, two isomers were describing the synthesis of "Torand" (Figure 1), only a few methods have been developed for the preparation of highly obtained due to the competition between 1,2-and 1,4-addition. The use of an aliphatic ternary iminium gives only soluble annelated polypyridines. [3] The introduction of solubility-improving carbon fragments into the central pyri-traces of the 1,4-addition isomer. dine rings can only take place in the 4-position because of to the annelated arrangement of these systems. The most In order to develop an efficient approach for the synthesis of polyalkylated annelated polypyridines, we decided important and useful approach for the preparation of these molecules are procedures involving 1,5-diketone intermedi-to investigate the Michael addition of β-alkylenones with enolizable cyclic ketones. We describe here the results, from ates which undergo ring closure forming the pyridines in the presence of a nitrogen-containing reagent.
an adaptation of this procedure, for the preparation of poly-
Figure 1
Recently, Bell [4] reported the syntheses of central 4-aryl-alkylated annelated bi-and terpyridines (Figure 2), which exhibit high solubility in organic solvents. substituted annelated terpyridine derivatives by condensation of 9-butyl-2,3,5,6,7,8-hexahydro-4(1H)-acridinone
We have recently developed an efficient synthetic method with arylenone derivatives in anhydrous DMSO containing based on the C-alkylation of enaminone derivatives with ammonium acetate, under modified Risch conditions. [5] Grignard reagents for the preparation of β-alkylenones. En-The β-arylenones employed in this procedure were prepared aminones 4؊6 were obtained in high yields by reaction of the corresponding ketones [6] [7] with 2 equivalents of N,N- [a] Laboratoire de Chimie de Coordination-CNRS UPR 8241, dimethylformamide dimethyl acetal [8] at 80°C for 8 h. En-