Reactions of Silica Chloride (SiO2Cl)/DMSO, a Heterogeneous System for the Facile Regeneration of Carbonyl Compounds from Thioacetals and Ring-Expansion Annelation of Cyclic Thioacetals

2002 ◽  
Vol 67 (8) ◽  
pp. 2572-2576 ◽  
Author(s):  
Habib Firouzabadi ◽  
Nasser Iranpoor ◽  
Hassan Hazarkhani ◽  
Babak Karimi
2000 ◽  
Vol 78 (9) ◽  
pp. 1194-1203
Author(s):  
Paul C Venneri ◽  
John Warkentin

A cyclopropanone, a cyclopropenone, cyclobutanones, a cyclobutane-1,3-dione, and a cyclobutene-1,2-dione reacted with dimethoxycarbene to afford acetals of the next larger ring by formal insertion of the carbene into a C—C bond α to the carbonyl group. When either of two saturated α-ring carbons could be involved in the process, the ring expansion was selective, affording primarily the product of apparent insertion into the more substituted ring bond. With 2,3-dimethoxycyclobutene-1,2-dione, insertion occurred between the carbonyl groups and with β-propiolactone it occurred at the lactone bond. β-Propiolactam, however, reacted by insertion of the carbene into the N—H bond.Key words: β-propiolactone, cyclobutanone, cyclobutananedione, cyclopropanone, dialkoxycarbene.


2019 ◽  
Vol 23 (17) ◽  
pp. 1843-1856
Author(s):  
Aditya Bhattacharyya

Partially reduced heterocyclic compounds such as 1,4,5,6-tetrahydropyrimidines are often found to possess interesting pharmacological properties. Yet, the synthetic routes towards such systems are less developed than their fully aromatic counterparts. In this review article, the biological significance of 1,4,5,6-tetrahydropyrimidines is discussed and the existing literature reports describing various preparative routes to access 1,4,5,6-tetrahydropyrimidine derivatives have been categorically described. The focus has been expanded to present an overview of the chronological development of the traditional synthetic routes as well as the contemporary approaches to 1,4,5,6-tetrahydropyrimidines that generally include: (i) condensation reactions of diamines with various appropriate counterparts such as carbonyl compounds, imino ethers, amidines or nitriles, condensation of amidines with 1,3-dibromopropane and α,β-unstaurated carbonyl compounds, condensation of amino alcohols; (ii) selective reduction of pyrimidines; (iii) ring expansion chemistry of cyclopropanes, aziridines, and azetidines; and (iv) miscellaneous examples such as various multicomponent reactions.


2007 ◽  
Author(s):  
T. A. Salama ◽  
S. S. Elmorsy ◽  
A. M. Khalil ◽  
M. A. Ismail ◽  
A. S. El-Ahl

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.


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