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ISSN 1998-9539

A Sterically Driven Approach to the Efficient Synthesis of Low-Symmetry 1,4-Diazepinoporphyrazines

Pavel A. Tarakanov,a@ Anton O. Simakov,b Ekaterina N. Tarakanova,a Alexander V. Chernyak,c,d Vladislav Klykov,e Pavel A. Stuzhin,e and Victor E. Pushkareva
aInstitute of Physiologically Active Compounds, Russian Academy of Sciences, 142432 Chernogolovka, Russian Federation
bHylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, N-0315 Oslo, Norway
cInstitute of Problems of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Russian Federation
dScience Center in Chernogolovka RAS, 142432 Chernogolovka, Russian Federation
eResearch Institute of Macroheterocycles, Ivanovo State University of Chemistry and Technology, 153000 Ivanovo, Russia
@Corresponding author E-mail: tarakanov_pa@ipac.ac.ru
 
DOI: 10.6060/mhc180484t
Macroheterocycles 2018 11(3) 312-315
 
We have investigated the general applicability of the synthetic procedure in which a carbonyl compound (in our case, 2,4-pentandione and 3-n-propyl-2,4-pentanedione) is added to a preformed TiCl4–diaminomaleonitrile complex for the preparation of 1,4-diazepine-2,3-dicarbonitriles. It has been shown that triethylamine commonly used as an auxiliary reagent (base) inhibits the formation of the TiCl4–diaminomaleonitrile complex and less basic pyridine  was proved to be more suitable. The introduction of the n-propyl group into the C6 position of 5,7-bis(2'-arylethenyl)-6H-1,4-diazepine-2,3-dicarbonitrile has led to an unprecedented increase in the yield of the low-symmetry A3B-type tribenzodiazepinoporphyrazine from 5 to 40 % under Linstead cross-macrocyclization conditions. The quantum-chemical calculations at the PW6B95-D3/def2-TZVP//BP86-D3/def2-TZVP level of theory demonstrated that steric effects of substituents in 6-alkyl substituted 5,7-bis(2′-arylethenyl)-6H-1,4-diazepine-2,3-dicarbonitriles can play a key role in formation of dimeric intermediates during Linstead macrocyclization, providing high selectivity towards low symmetry porphyrazines with annulated 1,4-diazepine heterocycle(s).

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