- Synthesis of the first conjugates of 5-ethynyl-2′-deoxyuridine with closo-dodecaborate and cobalt-bis-dicarbollide boron clusters
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A new 2′-deoxyuridine modification, 3′,5′-bis-(dimethyl- tert-butylsilyl)-5-(3-(2-(dimethylamino)ethoxy)-3-methylbutyn-1-yl) -2′-deoxyuridine was effectively synthesized in four easy steps. Its reactivity toward a range of cyclic oxonium adducts of closo-dodecaborate and cobalt-bis-dicarbollide boron clusters was studied. The cleavage reactions of cluster oxonium rings by the N,N-dimethylamino group of the modified nucleoside led to 5-ethynyl-2′-deoxyuridine conjugates with [B12H 12]2- and [Co(C2B9H 11)2]-, respectively. Cytotoxicity of these new conjugates in several cell lines was examined. Closo-dodecaborate conjugates showed low cytotoxicity in all examined cell lines, an advantageous and preferred property for potential boron delivering drugs for the boron neutron capture therapy (BNCT) of tumors.
- Semioshkin, Andrey,Ilinova, Anna,Lobanova, Irina,Bregadze, Vladimir,Paradowska, Edyta,Studzińska, Miros?awa,Jab?on?ska, Agnieszka,Lesnikowski, Zbigniew J.
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- Carbocyclization reaction of ω-iodo- and 1,ω-diiodo-1-alkynes without the loss of iodine atoms through a carbenoid-chain process
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(Chemical Equation Presented) Atom-economical carbocyclization reactions of ω-iodo-1-alkynes and 1,ω-diiodo-1-alkynes to give products with incorporation of iodine atoms is described. Cycloisomerization of 2-(2-propynyloxy)ethyl iodides is initiated by a catalytic amount of LDA to give 3-(iodomethylene)tetrahydrofurans in high yields. Upon treatment of with a catalytic amount of 1-hexynyllithium, 1ω-diiodo-1-alkynes efficiently undergo cycloisomerization to give (diiodomethylene)cycloalkanes. The diiodomethylene products are also obtained by iodine atom-transfer-type cyclization of ω-iodo-1-alkynes, using 1-iodo-1-hexyne as an external iodine atom source. Bromine atom-transfer and proton-transfer cyclization proceed as well by employing 1-bromo-1-octyne and 1-octyne, respectively. These reactions are proposed to proceed through a carbenoid-chain process involving exo-cyclization of the lithium acetylide intermediates to give Li,I-alkylidene carbenoids. It is shown that the exo-cyclization proceeded stereospecifically through inversion of the stereochemistry at the electrophilic carbon.
- Harada, Toshiro,Muramatsu, Keiko,Mizunashi, Kenia,Kitano, Chie,Imaoka, Daisuke,Fujiwara, Takayuki,Kataoka, Hiroshi
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p. 249 - 258
(2008/09/17)
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- NON NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS
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The invention relates to compounds of formula (I) wherein Ar, X, R1, R2, R3 and R4 are as defined herein and, pharmaceutical compositions thereof useful, either alone or in combination with other therapeutic agents as reverse transcriptase inhibitors against wild type and single or double mutant strains of HIV for the treatment or prophylaxis of HIV infection
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Page/Page column 91
(2008/06/13)
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