TY  - JOUR
AU  - Bjelaković, Mira
AU  - Krstić, Natalija
AU  - Tinant, Bernard
AU  - Kalvoda, Jaroslav
AU  - Csanadi, Janos
AU  - Pavlović, Vladimir D.
PY  - 2005
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4186
AB  - The conformations of (Z)‐ and (E)‐5‐oxo‐B‐nor‐5,10‐secocholest‐1(10)‐en‐3β‐yl acetates (2 and 3, resp.) were examined by a combination of X‐ray crystallographic analysis and NMR spectroscopy, with emphasis on the geometry of the cyclononenone moiety. The 1H‐ and 13C‐NMR spectra showed that the unsaturated nine‐membered ring of (E)‐isomer 3 in C6D6 and (D6)acetone solution exists in a sole conformation of type B1, which is similar to its solid‐state conformation. The (Z)‐isomer 2 in C6D6, CDCl3, and (D6)acetone solution, however, exists in two conformational forms of different families, with different orientation of the carbonyl group, the predominant form (85%) corresponding to the conformation of type A1 and the minor (15%) to the conformation A2 present also in the crystalline state. In this solid‐state conformations of the nine‐membered ring of both compounds, the 19‐Me and 5‐oxo groups are ‘β’‐oriented. The NMR analysis suggests that the nine‐membered ring of 4 has a conformation of type C1 in CDCl3 solution.
PB  - Wiley
T2  - Helvetica Chimica Acta
T1  - Conformations of the Nine-Membered Ring in the B-Nor-5,10-secosteroids. X-Ray and NMR Analysis
VL  - 88
IS  - 10
SP  - 2812
EP  - 2821
DO  - 10.1002/hlca.200590221
ER  - 

@article{
author = "Bjelaković, Mira and Krstić, Natalija and Tinant, Bernard and Kalvoda, Jaroslav and Csanadi, Janos and Pavlović, Vladimir D.",
year = "2005",
abstract = "The conformations of (Z)‐ and (E)‐5‐oxo‐B‐nor‐5,10‐secocholest‐1(10)‐en‐3β‐yl acetates (2 and 3, resp.) were examined by a combination of X‐ray crystallographic analysis and NMR spectroscopy, with emphasis on the geometry of the cyclononenone moiety. The 1H‐ and 13C‐NMR spectra showed that the unsaturated nine‐membered ring of (E)‐isomer 3 in C6D6 and (D6)acetone solution exists in a sole conformation of type B1, which is similar to its solid‐state conformation. The (Z)‐isomer 2 in C6D6, CDCl3, and (D6)acetone solution, however, exists in two conformational forms of different families, with different orientation of the carbonyl group, the predominant form (85%) corresponding to the conformation of type A1 and the minor (15%) to the conformation A2 present also in the crystalline state. In this solid‐state conformations of the nine‐membered ring of both compounds, the 19‐Me and 5‐oxo groups are ‘β’‐oriented. The NMR analysis suggests that the nine‐membered ring of 4 has a conformation of type C1 in CDCl3 solution.",
publisher = "Wiley",
journal = "Helvetica Chimica Acta",
title = "Conformations of the Nine-Membered Ring in the B-Nor-5,10-secosteroids. X-Ray and NMR Analysis",
volume = "88",
number = "10",
pages = "2812-2821",
doi = "10.1002/hlca.200590221"
}

Bjelaković, M., Krstić, N., Tinant, B., Kalvoda, J., Csanadi, J.,& Pavlović, Vladimir D.. (2005). Conformations of the Nine-Membered Ring in the B-Nor-5,10-secosteroids. X-Ray and NMR Analysis. in Helvetica Chimica Acta
Wiley., 88(10), 2812-2821.
https://doi.org/10.1002/hlca.200590221

Bjelaković M, Krstić N, Tinant B, Kalvoda J, Csanadi J, Pavlović V. Conformations of the Nine-Membered Ring in the B-Nor-5,10-secosteroids. X-Ray and NMR Analysis. in Helvetica Chimica Acta. 2005;88(10):2812-2821.
doi:10.1002/hlca.200590221 .

Bjelaković, Mira, Krstić, Natalija, Tinant, Bernard, Kalvoda, Jaroslav, Csanadi, Janos, Pavlović, Vladimir D., "Conformations of the Nine-Membered Ring in the B-Nor-5,10-secosteroids. X-Ray and NMR Analysis" in Helvetica Chimica Acta, 88, no. 10 (2005):2812-2821,
https://doi.org/10.1002/hlca.200590221 . .

TY  - JOUR
AU  - Bjelaković, Mira
AU  - Lorenc, Ljubinka
AU  - Pavlović, Vladimir D.
AU  - Tinant, Bernard
AU  - Declercq, Jean-Paul
AU  - Kalvoda, Jaroslav
PY  - 2003
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4187
AB  - Oxidations of 5α‐hydroxy‐B‐norcholestan‐3β‐yl acetate (8) with Pb(OAc)4 under thermal or photolytic conditions or in the presence of iodine afforded only complex mixtures of compounds. However, the HgO/I2 version of the hypoiodite reaction gave as the primary products the stereoisomeric (Z)‐ and (E)‐1(10)‐unsaturated 5,10‐seco B‐nor‐derivatives 10 and 11, and the stereoisomeric (5R,10R)‐ and (5S,10S)‐acetals 14 and 15 (Scheme 4). Further reaction of these compounds under conditions of their formation afforded, in addition, the A‐nor 1,5‐cyclization products 13 and 16 (from 10) and 12 (from 11) (see also Scheme 6) and the 6‐iodo‐5,6‐secolactones 17 and 19 (from 14 and 15, resp.) and 4‐iodo‐4,5‐secolactone 18 (from 15) (see also Scheme 7). Oxidations of 5β‐hydroxy‐B‐norcholestan‐3β‐yl acetate (9) with both hypoiodite‐forming reagents (Pb(OAc)4/I2 and HgO/I2) proceeded similarly to the HgO/I2 reaction of the corresponding 5α‐hydroxy analogue 8. Photolytic Pb(OAc)4 oxidation of 9 afforded, in addition to the (Z)‐ and (E)‐5,10‐seco 1(10)‐unsaturated ketones 10 and 11, their isomeric 5,10‐seco 10(19)‐unsaturated ketone 22, the acetal 5‐acetate 21, and 5β,19‐epoxy derivative 23 (Scheme 9). Exceptionally, in the thermal Pb(OAc)4 oxidation of 9, the 5,10‐seco ketones 10, 11, and 22 were not formed, the only reaction being the stereoselective formation of the 5,10‐ethers with the β‐oriented epoxy bridge, i.e. the (10R)‐enol ether 20 and (5S,10R)‐acetal 5‐acetate 21 (Scheme 8). Possible mechanistic interpretations of the above transformations are discussed.
PB  - Wiley
T2  - Helvetica Chimica Acta
T1  - Oxidative Fragmentations of the 5-alpha and 5-beta-Hydroxy-B-norcholestan-3-beta-yl Acetates
VL  - 86
IS  - 6
SP  - 2121
EP  - 2135
DO  - 10.1002/hlca.200390169
ER  - 

@article{
author = "Bjelaković, Mira and Lorenc, Ljubinka and Pavlović, Vladimir D. and Tinant, Bernard and Declercq, Jean-Paul and Kalvoda, Jaroslav",
year = "2003",
abstract = "Oxidations of 5α‐hydroxy‐B‐norcholestan‐3β‐yl acetate (8) with Pb(OAc)4 under thermal or photolytic conditions or in the presence of iodine afforded only complex mixtures of compounds. However, the HgO/I2 version of the hypoiodite reaction gave as the primary products the stereoisomeric (Z)‐ and (E)‐1(10)‐unsaturated 5,10‐seco B‐nor‐derivatives 10 and 11, and the stereoisomeric (5R,10R)‐ and (5S,10S)‐acetals 14 and 15 (Scheme 4). Further reaction of these compounds under conditions of their formation afforded, in addition, the A‐nor 1,5‐cyclization products 13 and 16 (from 10) and 12 (from 11) (see also Scheme 6) and the 6‐iodo‐5,6‐secolactones 17 and 19 (from 14 and 15, resp.) and 4‐iodo‐4,5‐secolactone 18 (from 15) (see also Scheme 7). Oxidations of 5β‐hydroxy‐B‐norcholestan‐3β‐yl acetate (9) with both hypoiodite‐forming reagents (Pb(OAc)4/I2 and HgO/I2) proceeded similarly to the HgO/I2 reaction of the corresponding 5α‐hydroxy analogue 8. Photolytic Pb(OAc)4 oxidation of 9 afforded, in addition to the (Z)‐ and (E)‐5,10‐seco 1(10)‐unsaturated ketones 10 and 11, their isomeric 5,10‐seco 10(19)‐unsaturated ketone 22, the acetal 5‐acetate 21, and 5β,19‐epoxy derivative 23 (Scheme 9). Exceptionally, in the thermal Pb(OAc)4 oxidation of 9, the 5,10‐seco ketones 10, 11, and 22 were not formed, the only reaction being the stereoselective formation of the 5,10‐ethers with the β‐oriented epoxy bridge, i.e. the (10R)‐enol ether 20 and (5S,10R)‐acetal 5‐acetate 21 (Scheme 8). Possible mechanistic interpretations of the above transformations are discussed.",
publisher = "Wiley",
journal = "Helvetica Chimica Acta",
title = "Oxidative Fragmentations of the 5-alpha and 5-beta-Hydroxy-B-norcholestan-3-beta-yl Acetates",
volume = "86",
number = "6",
pages = "2121-2135",
doi = "10.1002/hlca.200390169"
}

Bjelaković, M., Lorenc, L., Pavlović, Vladimir D., Tinant, B., Declercq, J.,& Kalvoda, J.. (2003). Oxidative Fragmentations of the 5-alpha and 5-beta-Hydroxy-B-norcholestan-3-beta-yl Acetates. in Helvetica Chimica Acta
Wiley., 86(6), 2121-2135.
https://doi.org/10.1002/hlca.200390169

Bjelaković M, Lorenc L, Pavlović V, Tinant B, Declercq J, Kalvoda J. Oxidative Fragmentations of the 5-alpha and 5-beta-Hydroxy-B-norcholestan-3-beta-yl Acetates. in Helvetica Chimica Acta. 2003;86(6):2121-2135.
doi:10.1002/hlca.200390169 .

Bjelaković, Mira, Lorenc, Ljubinka, Pavlović, Vladimir D., Tinant, Bernard, Declercq, Jean-Paul, Kalvoda, Jaroslav, "Oxidative Fragmentations of the 5-alpha and 5-beta-Hydroxy-B-norcholestan-3-beta-yl Acetates" in Helvetica Chimica Acta, 86, no. 6 (2003):2121-2135,
https://doi.org/10.1002/hlca.200390169 . .

TY  - JOUR
AU  - Bjelaković, Mira
AU  - Lorenc, Ljubinka
AU  - Pavlović, Vladimir D.
AU  - Mihailović, Milhailo Lj.
AU  - Tinant, Bernard
AU  - Declercq, Jean-Paul
AU  - Kalvoda, Jaroslav
PY  - 1999
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4184
AB  - Oxidations of 14α‐hydroxy‐5α‐cholestan‐3β‐yl acetate (5) with lead tetraacetate under thermal or photolytic conditions or in the presence of iodine proceed mainly by fragmentation of the C(13)−C(14) bond to give as the primary products the 13,18‐didehydro‐13,14‐seco derivative 6 and the (E )‐Δ12‐13,14‐seco ketone 11, respectively. Further transformations of these compounds under conditions of their formation afforded, in addition, the acetoxy derivatives 7 – 9 (from 6), and the D‐homo‐C‐nor compound 12 and (12R,13R)‐epoxide 13 (from 11). Unexpectedly, the photolytic lead‐tetraacetate oxidation of 5 resulted partly (to ca. 20%) in a reversible fragmentation involving scission and recombination of the C(8)−C(14) bond followed by formation of the 14β,22‐ether 10. Possible mechanisms for the observed transformations are discussed.
PB  - Wiley
T2  - Helvetica Chimica Acta
T1  - 13,14-Seco-steroids: A New Type of Modified Steroids Containing a Nine-Membered Ring
VL  - 82
IS  - 5
SP  - 707
EP  - 721
DO  - 10.1002/(SICI)1522-2675(19990505)82:5<707::AID-HLCA707>3.0.CO;2-O
ER  - 

@article{
author = "Bjelaković, Mira and Lorenc, Ljubinka and Pavlović, Vladimir D. and Mihailović, Milhailo Lj. and Tinant, Bernard and Declercq, Jean-Paul and Kalvoda, Jaroslav",
year = "1999",
abstract = "Oxidations of 14α‐hydroxy‐5α‐cholestan‐3β‐yl acetate (5) with lead tetraacetate under thermal or photolytic conditions or in the presence of iodine proceed mainly by fragmentation of the C(13)−C(14) bond to give as the primary products the 13,18‐didehydro‐13,14‐seco derivative 6 and the (E )‐Δ12‐13,14‐seco ketone 11, respectively. Further transformations of these compounds under conditions of their formation afforded, in addition, the acetoxy derivatives 7 – 9 (from 6), and the D‐homo‐C‐nor compound 12 and (12R,13R)‐epoxide 13 (from 11). Unexpectedly, the photolytic lead‐tetraacetate oxidation of 5 resulted partly (to ca. 20%) in a reversible fragmentation involving scission and recombination of the C(8)−C(14) bond followed by formation of the 14β,22‐ether 10. Possible mechanisms for the observed transformations are discussed.",
publisher = "Wiley",
journal = "Helvetica Chimica Acta",
title = "13,14-Seco-steroids: A New Type of Modified Steroids Containing a Nine-Membered Ring",
volume = "82",
number = "5",
pages = "707-721",
doi = "10.1002/(SICI)1522-2675(19990505)82:5<707::AID-HLCA707>3.0.CO;2-O"
}

Bjelaković, M., Lorenc, L., Pavlović, Vladimir D., Mihailović, M. Lj., Tinant, B., Declercq, J.,& Kalvoda, J.. (1999). 13,14-Seco-steroids: A New Type of Modified Steroids Containing a Nine-Membered Ring. in Helvetica Chimica Acta
Wiley., 82(5), 707-721.
https://doi.org/10.1002/(SICI)1522-2675(19990505)82:5<707::AID-HLCA707>3.0.CO;2-O

Bjelaković M, Lorenc L, Pavlović V, Mihailović ML, Tinant B, Declercq J, Kalvoda J. 13,14-Seco-steroids: A New Type of Modified Steroids Containing a Nine-Membered Ring. in Helvetica Chimica Acta. 1999;82(5):707-721.
doi:10.1002/(SICI)1522-2675(19990505)82:5<707::AID-HLCA707>3.0.CO;2-O .

Bjelaković, Mira, Lorenc, Ljubinka, Pavlović, Vladimir D., Mihailović, Milhailo Lj., Tinant, Bernard, Declercq, Jean-Paul, Kalvoda, Jaroslav, "13,14-Seco-steroids: A New Type of Modified Steroids Containing a Nine-Membered Ring" in Helvetica Chimica Acta, 82, no. 5 (1999):707-721,
https://doi.org/10.1002/(SICI)1522-2675(19990505)82:5<707::AID-HLCA707>3.0.CO;2-O . .

TY  - JOUR
AU  - Todorović, Nina
AU  - Stefanović, Milutin
AU  - Tinant, Bernard
AU  - Declercq, Jean-Paul
AU  - Makler, Michael T
AU  - Šolaja, Bogdan
PY  - 1996
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/3995
AB  - Cholestane-derived gem-dihydroperoxides and tetraoxanes were synthesized starting from 5e~- and 5~3-cholestan3-ones by acid-catalyzed addition of hydrogen peroxide to the ketone. They were characterized by IR, NMR, and
mass spectroscopy analysis aided by molecular mechanics calculations, and, in the instance of 5~3-cholestane3et,3~5-dihydroperoxide (6), by x-ray analysis. The synthesized compounds were tested in vitro against Plasmodium falciparum Sierra Leone (D6) and Indochina (W2) malaria clones. All compounds" were inactive to
both clones, with the exception of tetraoxane 7a, which exhibited modest activity toward D6 clone with IC5o =
155 nM
PB  - Elsevier
T2  - Steroids
T1  - Steroidal geminal dihydroperoxides and 1,2,4,5-tetraoxanes: Structure determination and their antimalarial activity
VL  - 61
IS  - 12
SP  - 688
EP  - 696
DO  - 10.1016/S0039-128X(96)00203-6
ER  - 

@article{
author = "Todorović, Nina and Stefanović, Milutin and Tinant, Bernard and Declercq, Jean-Paul and Makler, Michael T and Šolaja, Bogdan",
year = "1996",
abstract = "Cholestane-derived gem-dihydroperoxides and tetraoxanes were synthesized starting from 5e~- and 5~3-cholestan3-ones by acid-catalyzed addition of hydrogen peroxide to the ketone. They were characterized by IR, NMR, and
mass spectroscopy analysis aided by molecular mechanics calculations, and, in the instance of 5~3-cholestane3et,3~5-dihydroperoxide (6), by x-ray analysis. The synthesized compounds were tested in vitro against Plasmodium falciparum Sierra Leone (D6) and Indochina (W2) malaria clones. All compounds" were inactive to
both clones, with the exception of tetraoxane 7a, which exhibited modest activity toward D6 clone with IC5o =
155 nM",
publisher = "Elsevier",
journal = "Steroids",
title = "Steroidal geminal dihydroperoxides and 1,2,4,5-tetraoxanes: Structure determination and their antimalarial activity",
volume = "61",
number = "12",
pages = "688-696",
doi = "10.1016/S0039-128X(96)00203-6"
}

Todorović, N., Stefanović, M., Tinant, B., Declercq, J., Makler, M. T.,& Šolaja, B.. (1996). Steroidal geminal dihydroperoxides and 1,2,4,5-tetraoxanes: Structure determination and their antimalarial activity. in Steroids
Elsevier., 61(12), 688-696.
https://doi.org/10.1016/S0039-128X(96)00203-6

Todorović N, Stefanović M, Tinant B, Declercq J, Makler MT, Šolaja B. Steroidal geminal dihydroperoxides and 1,2,4,5-tetraoxanes: Structure determination and their antimalarial activity. in Steroids. 1996;61(12):688-696.
doi:10.1016/S0039-128X(96)00203-6 .

Todorović, Nina, Stefanović, Milutin, Tinant, Bernard, Declercq, Jean-Paul, Makler, Michael T, Šolaja, Bogdan, "Steroidal geminal dihydroperoxides and 1,2,4,5-tetraoxanes: Structure determination and their antimalarial activity" in Steroids, 61, no. 12 (1996):688-696,
https://doi.org/10.1016/S0039-128X(96)00203-6 . .