Romanian Society of Pharmaceutical Sciences
 

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COMPUTATIONAL SEARCH FOR LONG BONDS IN RADICAL CATIONS OF SUGARS 1. GLUCOFURANOSE, GALACTOFURANOSE AND MANNOFURANOSE DI-O-ISOPROPYLIDENE DERIVATIVES

MIHAI-COSMIN PASCARIU1, MADIAN RAFAILĂ2, MIHAI MEDELEANU2, VALENTIN BADEA2, ALEXANDRA TEODORA GRUIA3, VICTOR LORIN PURCAREA4, MIRCEA PENESCU4,5, EUGEN SISU6*

1.“Vasile Goldiş” Western University of Arad, Faculty of Pharmacy, 86 Liviu Rebreanu, 310045, Arad, Romania
2 .University Politehnica Timişoara, Faculty of Industrial Chemistry and Environmental Engineering, 6 Carol Telbisz,
30 0001, Timişoara, Romania
3 .Clinical County Hospital of Timișoara, Immunology of Transplant Department, 10 Iosif Bulbuca Blvd., 300736, Timişoara,
Romania
4 .“Carol Davila” University of Medicine and Pharmacy, 37 Dionisie Lupu, 020021, Bucharest, Romania
5 .“Carol Davila” Hospital of Nephrology, 4 Calea Griviței, 010731, Bucharest, Romania
6 .“Victor Babeş” University of Medicine and Pharmacy of Timișoara, Faculty of Medicine, 2 Eftimie Murgu Sq., 300041,
Timișoara, Romania

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The di-O-isopropylidene derivatives of aldohexoses, in their furanose form, are easily recognized during positive mode electron ionization mass spectrometry analysis because they all exhibit a strong intensity peak at m/z 101, which is usually the base peak. The literature data indicate that this peak appears due to the 2,2-dimethyl-1,3-dioxolan-4-ylium ion, which is formed through the detachment of the exocyclic dioxolane acetal. In the molecular ion, the radical character seems to be localized at the conjunction between the exocyclic dioxolane acetal and the furanose hemiacetal, the carbon-carbon bond between the two rings thus gaining a long bond character. We have used semi-empirical calculations to prove that such long bonds represent a rational explanation for the genesis of the m/z 101 cation in diastereomeric hexofuranose diacetals and their alkyl derivatives. The theoretical results seem to confirm the conclusions resulted from the analysis of mass spectra acquired for a series of furanose compounds.