- The synthesis of 6-deazaformycin A
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The synthesis of the new C-nucleoside 6-deazaformycin A was achieved through the condensation of a suitably substituted lithiated 2-picoline with 2,3,5-tri-O-benzyl-d-ribonolactone, borohydride reduction of the resulting hemiacetals, followed by intramolecular Mitsunobu cyclization of the carbinols, manipulation of the protecting groups, and subsequent ring closure to result in the formation of 7-amino-3-(β-d-ribofuranosyl)pyrazolo[4,3-b]pyridine. Georg Thieme Verlag Stuttgart.
- Tite, Tony,Lougiakis, Nikolaos,Marakos, Panagiotis,Pouli, Nicole
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scheme or table
p. 2927 - 2930
(2010/02/28)
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- Efficient catalytic conversion of pyridine N-oxides to pyridine with an oxorhenium(V) catalyst
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(Equation Presented) The compound CH3Re(O)(SR)2PPh3, where (SR)2 represents the dianion of 2-(mercaptomethyl)thiophenol, catalyzes the rapid and efficient transfer of an oxygen atom from a wide range of ring-substituted pyridine N-oxides to triphenylphosphine, yielding the pyridines in high yield.
- Wang, Ying,Espenson, James H.
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p. 3525 - 3526
(2007/10/03)
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- Selective deoxygenation of heteroaromatic N-oxides with olefins catalyzed by ruthenium porphyrin
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A new convenient method of deoxygenation of heteroaromatic N-oxides is described. Ruthenium porphyrin was used as a catalyst and this method expressed high yields for o-substituted pyridine N-oxides, quinoline N-oxide derivatives, acridine N-oxide, etc. under mild conditions. Moreover, nitro-, benzyloxy-, and ketone carbonyl groups, which can be affected by the usual deoxygenation methods such as catalytic hydrogenation or borane reduction, were retained.
- Nakagawa, Hiroshi,Higuchi, Tsunehiko,Kikuchi, Kazuya,Urano, Yasuteru,Nagano, Tetsuo
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p. 1656 - 1657
(2007/10/03)
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- Synthesis of Petrosins C and D
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Petrosins C and D (5 and 6), diastereomers of the known natural products petrosin (1), petrosin A (2), and petrosin B (3), have been prepared. The synthetic route involved initial creation of a 16-membered bis-pyridine intermediate, exemplified by compounds 7, 28, and 52. Several different methods for formation of the macrocycle were evaluated, and the most efficient (Schemes 7-9) involved use of Z double bonds in the six-carbon chains linking the two pyridine rings. This approach permitted the two pyridine subunits (37 and 39) to be joined by alkylation of a lithiated α-methylpyridine with an allylic chloride (e.g., 37 + 39 → 40 and 49 → 45). Bisannulation of compounds 7 and 28 was complicated by a surprising lack of acidity of the α-pyridyl methylene groups Eventually, this problem was solved by stepwise introduction of two allyl groups, using the more acidic sulfone for introduction of the first (e.g., 52 → 53) and direct allylation to introduce the second (e.g., 54 → 55 + 56). The bisannulation was completed by hydroboration and conversion of the primary alcohols into methanesulfonate derivatives, which cyclized to afford bis-pyridinium derivatives. Reduction of these intermediate salts with sodium borohydride provided crystalline bis-enol ethers (60 and 63) and the relative configuration was established by single-crystal X-ray analysis of 63. After hydrolysis of the enol ethers to the corresponding ketones, the syntheses of 5 and 6 were completed by enolate methylation. As expected, compounds 5 and 6 do not form imine derivatives when treated with primary amines, presumably because of A1,3 strain.
- Heathcock, Clayton H.,Brown, Richard C. D.,Norman, Thea C.
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p. 5013 - 5030
(2007/10/03)
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- 8-Arylalkyl- and 8-arylheteroalkyl-5, 11-dihydro-6H-dipyrido-[3,2-b:2', 3'-e][1,4]diazepines and their use in the prevention or treatment of HIV infection
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The invention relates to novel 8-arylalkyl-5,11-dihydro-6H-dipyrido[3,2-b:2',3'-e][1,4]diazepines of general formula 1 which are useful in the prevention or treatment of HIV infection.
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