Ivan F. Tsymbal

Synthesis, Conformation, and Binding Properties of Resorcarene Tetrasulfonates. Asymmetric Reorganization of Pendant Sulfonyl Groups via Intramolecular SO- - -H−O Hydrogen Bonds

The regioselective reaction of resorcarene octaols 1 with 4 equiv of arylsulfonyl chlorides and Et3N in MeCN gives in 30−60% yield the C2v symmetrical tetrasulfonates 3. The mild electrophilic substitution (aminomethylation, bromination) of resorcarene tetrasulfonates 3 and tetraphosphates 2 takes place only in the 2-positions of unsubstituted resorcinol rings yielding distally disubstituted resorcarenes 4. The acylation of hydroxy groups in compounds 2 and 3 gives C2v symmetrical octaesters 5 including large resorcarene tetracrown-ethers. In the minimized boat conformation of tetrasulfonates 3 the two unsubstituted resorcinol rings are vertical and the sulfonyl fragments are arranged in a C2 symmetrical manner via intramolecular SO- - -H−O hydrogen bonds. This structure is proved by NMR and IR spectroscopy. In the case of tetrasulfonate 3c the two enantiomeric conformations interconvert in CDCl3 with ΔG* = 11.6 kcal/mol. This is in agreement with the ΔE* value predicted by molecular mechanics in vacuo.

Heterocyclization of functionalized heterocumulenes with C,N- and C,O-binucleophiles: IV. Reactions of 1-chloroalkylheterocumulenes and N-(1-chloroalkylidene)carbamates with 2-benzimidazolylacetonitriles and methyl 2-benzimidazolylacetates

Abstract1-Chloroalkyl isocyanates and 1-chloroalkylcarbodiimides undergo regioselective cyclization with nitriles and esters of 2-benzimidazolylacetic acid to give derivatives of 1-oxo and 1-arylimino-1,2,3,5-tetrahydrobenzo[4,5]imidazo[1,2-c]pyrimidine respectively. The cyclocondensation of 1,1-dichloroalkyl isocyanates or N-(1-chloroalkylidene)carbamates with nitriles and esters of 2-benzimidazolylacetic acid afforded 1,5-dihydrobenzo[4,5]imidazo[1,2-c]pyrimidin-1-one derivatives.

Heterocyclization of Functionalized Heterocumulenes with C,N- and C,O-Binucleophiles. 1. Cyclocondensation of 1-Chloroalkylheterocumulenes and N-(1-Chloroalkylidene)urethanes with 2-Cyanomethylpyridine

The interaction of 1-chloroalkyl isocyanates, 1-chloroalkylcarbodiimides, 1,1-dichloroalkyl isocyanates, and N-(1-chloroethylidene)-O-methylurethanes with 2-cyanomethylpyridine has been investigated. An effect of organic base has been detected on the regioselectivity of the cyclocondensation of 1-chloroalkyl isocyanates, which leads to 2,3-dihydro-1H-pyrido[1,2-c]pyrimidin-1-one or the isomeric 2,3-dihydro-1H-pyrido[1,2-c]pyrimidin-3-one. Irrespective of the cyclization conditions 1-chloroalkylcarbodiimides react with the formation of 1-imino-2,3-dihydro-1H-pyrido[1,2-c]pyrimidines. One type of product, a 1H-pyrido[1,2-c]pyrimidin-1-one, was also isolated from 1,1-dichloroalkyl isocyanates and N-(1-chloroalkylidene)urethanes.

Heterocyclization of functionalized heterocumulenes with C,N-, C,O-, and C,S-Binucleophiles: XI. Synthesis of dialkyl 2-oxo-3,6-diaryl-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates by cyclocondensation of 1-chlorobenzyl isocyanates with dialkyl anilinofumarates

Abstract1-Chlorobenzyl isocyanates react with N-arylfumarates with the formation of dialkyl 2-oxo-3,6-diaryl-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates that on alkaline hydrolysis are converted into 6-alkoxycarbonyl-1,4-diaryl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acids. The condensation of 1-chloro-1-phenyl-2,2,2-trifluoroethyl isocyanate with N-arylfumarates results in dialkyl 6-oxo-2,3-diaryl-2-trifluoromethyl-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates.