INFLUENCE OF HYDROGEN BONDS ON THE MOLECULAR STRUCTURE AND CONFORMATIONS OF TWO (C30H48O2) PENTACYCLIC TRITERPENE ISOMERS
R.S. Corr??a1, S.R. Souza e silva2, L.P. Duarte2, G.D.F. Silva2, L.C.A. Barbosa3, J. Ellena4, A.C. Doriguetto1
1 Instituto de Química, Universidade Federal de Alfenas - UNIFAL-MG
2 Departamento de Química, ICEX, Universidade Federal de Minas Gerais - UFMG
3 Departamento de Química, Universidade Federal de Viçosa
4 Departamento de Física e Informática, Instituto de Física de São Carlos - USP
doriguetto@unifal-mg.edu.br
Ключевые слова: Maytenus imbricata, pentacyclic triterpene, crystal structure, molecular conformation, static disorder, hydrogen bond
Страницы: 160-166
Аннотация
The structural study of two (C30H48O2) pentacyclic triterpene (PCTT) isomers is presented. These terpenes, known as 30-hydroxy-lup-20(29)-en-3-one (1) and (11α)-11-hydroxy-lup-20(29)-en-3-one (2), were isolated from Maytenus imbricata Mart. Ex Reissek (Celastraceae). The molecular structure of 1 and 2 differs in the position of the hydroxyl group. Both compounds crystallize in non-centrosymmetric space groups with two molecules in the asymmetric unit. The crystal structure of 1 shows a triclinic P1 space group (a = 9.5518(1) Å, b = 9.7083(1) Å, c = 14.4696(2) Å, α = 93.832(1)°, β = 102.833(1)° and γ = 103.307(1)°), while compound 2 crystallizes in a monoclinic P21 one (a = 13.4439(16) Å, b = 14.4463(14) Å, c = 13.5224(9) Å and β = 99.703(8)°). The two molecules independent by symmetry of 1 differ slightly due to the presence of static disorder in oxygen atoms. In addition, the intermolecular geometries of 1 and 2 were analysed, and in each isomer the crystal packing is stabilized by O-H⋯O intermolecular hydrogen bonds and van der Waals forces.
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