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1
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84918604400
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G.H. Veeneman and J.H. van Boom, Tetrahedron Lett., in press.
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2
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84918634679
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G.H. Veeneman and J.H. van Boom, manuscript in preparation.
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3
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0018252891
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NIS was shown to be an effective reagent in the hydrolysis of dithioketals
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(1978)
J. Am. Chem. Soc.
, vol.100
, pp. 7069
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Burri1
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4
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0042527922
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Iodohydrins and iodohydrin esters. VI. A general procedure for the preparation of trans-1,2-iodocarboxylates
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NIS in the presence of vadons carboxylic acids reacts readily with cyclohexone to give the corresponding trans-1,2 iodocurboxylates, This reaction proceeds presumably via an iodoniumcarboxylate intermediate in which the iodonium ion is more electrophilic compared to NIS.
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(1976)
Tetrahedron Letters
, vol.40
, pp. 3661]
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Adinolfi1
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5
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84918602267
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4 (0.15 eq.) in dichloromethane at 0°C, followed by Zemplén deacetylation and subsequent benzoylation (BzCl-pyridine). Rhamnose donor 8 was prepared as described previously [G.H. Veeneman ., Tetrahedron, in press]. Compound 9 was obtained by processing the corresponding β-acetate with ethanethiol as described above.
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6
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84918651023
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13C (δ values), 4α, 89.9 (C-1); 4β, 94.0 (C-1); 6a, 92.3 (C-1); 6b, 93.0 (C-1); 6c, 92.4 (C-1); 6d, 94.6 (C-1).
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10
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84918602674
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+A (A=TfO), generated in Eq. 1, activates the thiogiycoside (see Eq. 2) resulting, after a cascade of events, in the continuous regeneration of TfOH: thus illustrating the catalytic role of TfOH in the giycosidation process.
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11
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0024427662
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n-Pentenyl glycosides facilitate a stereoselective synthesis of the pentasaccharide core of the protein membrane anchor found in Trypanosoma brucei
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Recently,Fraser-Reid reported on the use of NIS/TfOH for the activation of “armed” and “disarmed” n-pentenyl mannosides, In this respect it is of interest to note the following. In a comparitive experiment we observed that glycosidation of n-pentenyl 2,3,4,6-tetra-O-bonzoyl-β-D-giucopyranoside with aglycon 10 in the presence of equimolar amounts of NIS and TfOH was, under these conditions, not complete after 45 min. On the other hand, when the same condensation was performed with donor 7 the reaction was complete after 20 sec. These observed differences in rate may open the way of condensing “disarmed” thioglycoside donors with either “armed” or “disarmed” n-pentenyl acceptors.
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(1989)
Journal of the American Chemical Society
, vol.111
, pp. 8540
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12
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84918596842
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3): 15, 102.1 (C-1′), 96.3 (C-1); 16, 101.3 (C-1′), 100.0 (C-1); 17, 101.9 (C-1′), 99.5 (C-1); 18, 98.7 (C-1′), 96.6 (C-1); 19, 102.3 (C-1′), 96.7 (C-1); 20, 99.1 and 97.3 (C-1′ and C-1″), 96.6 (C-1); 21, 99.5 (C-1), 99.2 (C-1′); 22, 99.0 (C-1′), 96.6 (C-1); 23 (α-isomer), 96.7 (C-1′), 98.6 (C-1).
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20
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0001781182
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Compounds 6a-d are valuable g1ycosyl donors in a Lewis acid-catalyzed glycosidation procedure see e.g., This option is currently under investigation in our laboratory.
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(1984)
Carbohydr. Res.
, vol.135
, pp. 53
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Paulsen1
Paal2
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