28899-97-0Relevant articles and documents
Mechanistic Studies of Bismuth(V)-Mediated Thioglycoside Activation Reveal Differential Reactivity of Anomers
Goswami, Manibarsha,Ashley, Daniel C.,Baik, Mu-Hyun,Pohl, Nicola L. B.
, p. 5949 - 5962 (2016)
The mechanism of bismuth(V)-mediated thioglycoside activation was examined using reaction kinetics and quantum chemical reaction models. NMR experiments show an unusual nonlinear growth/decay curve for the glycosylation reaction. Further studies suggest an anomeric inversion of the β-glycoside donor to the α-donor during its activation, even in the presence of a neighboring 2-position acetate. Interestingly, in situ anomerization was not observed in the activation of an α-glycoside donor, and this anomer also showed faster reaction times and higher product diastereoselectivites. Density functional theory calculations identify the structure of the promoter triphenyl bismuth ditriflate, [Ph3Bi(OTf)2, 1], in solution and map out the energetics of its interactions with the two thioglycoside anomers. These calculations suggest that 1 must bind the thiopropyl arm to induce triflate loss. The computational analyses also show that, unlike most O-glycosides, the β- and α-donor S-glycosides are similar in energy. One energetically reasonable anomerization pathway of the donors is an SN1-like mechanism promoted by forming a bismuth-sulfonium adduct with the Lewis acidic Bi(V) for the formation of an oxacarbenium intermediate. Finally, the computed energy compensations needed to form these α vs β Bi adducts is a possible explanation for the differential reactivity of these donors.
Facile one-pot synthesis of triphenylbismuth(V) bis(carboxylate) complexes
Kumar, Ish,Bhattacharya, Prateek,Whitmire, Kenton H.
, p. 2906 - 2909 (2014/06/24)
Triphenylbismuth(V) bis(carboxylates), Ph3Bi(O 2CR)2 (R = 5-Br-2-OH-C6H3 (1), 2-OH-C6H4 (2), 2,6-(OH)2-C6H 3 (3), 3-Me-2-NH2-C6H3 (4), Ph (5), Me (6)), were obtained from the reaction of triphenylbismuth with hydrogen peroxide and excess carboxylic acid in wet 2-propanol. The synthesis avoids the use of halogens as oxidants, and the products crystallize directly from the solution as pure compounds. They crystallize from solution without further need for purification. The structures of 1-5 were confirmed by single-crystal X-ray diffraction. Compounds 2 and 5 exhibit a polymorph different from that previously reported in the literature. While all of the Bi(V) compounds adopt a trans-axial trigonal-bipyramidal configuration with the carboxylates in axial positions, there is considerable variation in the coordination of the carboxylate that ranges from simple η1 to a mixture of mono- and bidentate chelating bonding modes.
3-SUBSTITUTED QUINOLINIUM AND 7H-INDOLO[2,3-c]QUINOLINIUM SALTS AS NEW ANTIINFECTIVES
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Page/Page column 12, (2012/07/13)
The present invention relates to quinolinium antiinfective agents in which the qunolinium nucleus is fused to an indole ring or the qunolinium nucleus is linked to a cyclic structure through an opened indole or a benzothiophene or benzofuran ring. The compound is further substituted with various substituent groups. The compounds are represented by formula (I), (II) and (III): Pharmaceutical compositions and methods of use are also included.
