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Bismuth(III) Reagents in Steroid and Terpene Chemistry
Salvador, Jorge A. R.; Silvestre, Samuel M.; Pinto, Rui M. A.Steroid and terpene chemistry still have a great impact on medicinal chemistry. Therefore, the development of new reactions or “greener” processes in this field is a contemporaneous issue. In this review, the use of bismuth(III) salts, as “ecofriendly” reagents/catalysts, on new chemical processes involving steroids and terpenes as substrates will be focused. Special attention will be given to some mechanistic ...
Novel semisynthetic derivatives of betulin and betulinic acid with cytotoxic ac...
Santos, Rita C.; Salvador, Jorge A. R.; Marín, Silvia; Cascante, MartaA series of new imidazole carboxylic esters (carbamates) and N-acylimidazole derivatives of betulin and betulinic acid (14-29) have been synthesized. The new compounds were screened for in vitro cytotoxicity activity against human cancer cell lines HepG2, Jurkat and HeLa. A number of compounds have shown IC50 values lower than 2 [mu]M against the cancer cell lines tested and the vast majority has shown a better...
3-Oxoandrosta-4,6-dien-17[beta]-yl 2-methyl-1H-imidazole-1-carboxylate and 3-ox...
Silva, Manuela Ramos; Moreira, Vânia M.; Cardoso, Cláudia; Beja, Ana Matos; Salvador, Jorge A. R.The title compounds, C24H30N2O3, (I), and C24H34N2O3, (II), both contain an androstane backbone and a 2-methylimidazole-1-carboxylate moiety at the 17-position. Compound (I) contains two symmetry-independent molecules (denoted 1 and 2), while compound (II) contains just one molecule in the asymmetric unit. The C-C-O-C torsion angle that reflects the twisting of the 2-methylimidazole-1-carboxylate moiety from th...
Metal triflates combined with caffeine based imidazolium salts: A new family of...
Pinto, Rui M. A.; Salvador, Jorge A. R.; Roux, Christophe LeThe direct alkylation of caffeine (1), by ethyl triflate gave 1,3,7-trimethyl-9-ethylxanthinium triflate (2) which led to 1,3,7-trimethyl-9-ethylxanthinium bis(trifluoromethanesulfonyl)amide (3) after methathesis with LiNTf2; 3 proved to be an ionic solid which can be used for the recovery of metal triflates (M(OTf)n with M = Sc, La, Yb, Cu, Hf, Bi). These reusable catalysts proved to be efficient Lewis acids f...
5β,6β-Epoxy-17-oxoandrostan-3β-yl acetate and 5β,6β-epoxy-20-oxopregnan-3β-yl a...
Pinto, Rui M. A.; Salvador, Jorge A. R.; Paixão, José A.In the title compounds, C21H30O4, (I), and C23H34O4, (II), respectively, which are valuable intermediates in the synthesis of important steroid derivatives, rings A and B are cis-(5β,10β)-fused. The two molecules have similar conformations of rings A, B and C. The presence of the 5β,6β-epoxide group induces a significant twist of the steroid nucleus and a strong flattening of the B ring. The different C17 subst...
Conformation of 17-chloro-16-formylandrosta-5,16-dien-3[beta]-yl acetate and 17...
Silva, Manuela Ramos; Moreira, Vânia M.; Cardoso, Cláudia; Beja, Ana Matos; Salvador, Jorge A. R.In the title compounds, C22H29ClO3, (I), and C21H29ClO2, (II), respectively, the B rings adopt a half-chair conformation and the D rings adopt an envelope conformation. A twist of the steroid skeleton of both compounds is observed. There is a positional disorder of the acetoxy group of (II), with the terminal atoms disordered over two positions with near equal occupancy. Quantum-mechanical ab initio calculation...
Synthesis and evaluation of novel 17-indazole androstene derivatives designed a...
Moreira, Vânia M. A.; Vasaitis, Tadas S.; Njar, Vincent C. O.; Salvador, Jorge A. R.A series of novel 1H- and 2H-indazole derivatives of the commercially available dehydroepiandrosterone acetate have been synthesized and tested for inhibition of human cytochrome 17 -hydroxylase-C17,20-lyase (CYP17), androgen receptor (AR) binding affinity, and cytotoxic potential against three prostate cancer (PC) cell lines.
Synthesis and evaluation of novel 17-indazole androstene derivatives designed a...
Moreira, Vânia M. A.; Vasaitis, Tadas S.; Njar, Vincent C. O.; Salvador, Jorge A. R.A series of novel 1H- and 2H-indazole derivatives of the commercially available dehydroepiandrosterone acetate have been synthesized and tested for inhibition of human cytochrome 17[alpha]-hydroxylase-C17,20-lyase (CYP17), androgen receptor (AR) binding affinity, and cytotoxic potential against three prostate cancer (PC) cell lines. ; http://www.sciencedirect.com/science/article/B6TC9-4PF1WHS-2/1/094a9de6c64...
Allylic and benzylic oxidation reactions with sodium chlorite
Silvestre, Samuel M.; Salvador, Jorge A. R.Various allylic and benzylic substrates were selectively oxidized to the corresponding enones in good yields using sodium chlorite, either in combination with tert-butyl hydroperoxide in stoichiometric conditions, or associated with N-hydroxyphthalimide as catalyst. These oxidation reactions were effectively and economically performed under mild, transition-metal free conditions and therefore the dual challenge...
Bismuth-catalyzed allylic oxidation using t-butyl hydroperoxide
Salvador, Jorge A. R.; Silvestre, Samuel M.Bismuth(III) salts are efficient catalysts for the selective allylic oxidation using tert-butyl hydroperoxide. BiCl3 is especially effective and can be easily recovered and reused as BiOCl. Using BiCl3/K-10 as catalyst, an increase in the reaction rate was observed. ; http://www.sciencedirect.com/science/article/B6THS-4FM3WXK-3/1/d89629a08a7ed175593fb6938b963a34
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