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1
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77956948298
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Organic Synthesis with Sulfur Heterocycles (Thiazoles) as Auxiliaries. The Thiazole Route to Carbohydrates and Biologically Active Derivatives
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Thiazole Route to Carbohydrates : Synthesis of building blocks or precursors to carbohydrates and related compounds using functionally substituted thiazoles. For recent accounts see :
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(1989)
Phosphorus, Sulfur, and Silicon and the Related Elements
, vol.43
, pp. 25
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Dondoni1
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11
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84918147768
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The mercury-mediated hydrolysis of the thiazolidine ring to the formyl group does not tolerate a free amino group. The conversion to an amidic function such as N-Boc (ref. 2a) or N-Acetyl Dondoni, A. Fantin, G. Fogagnolo, M. Medici, A. Pedrini, P. Tetrahedron,1988, 44 3215, overcomes this problem
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12
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84918147767
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The low isolated yield of 8c asks for modified conditions to make this functionalization synthetically useful.
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18
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84918147766
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Results from our ongoing work in this area will be published in due course.
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38
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84918147765
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The degree of selectivity was not improved by addition of LiBr and the change of the solvent ( methylene dichloride, 1,2-dichloroethane, chloroform, THF, DMF) and base ( n-BuLi, THF). Z- selectivity (90 : 10) was observed using the preformed phosphorane 1 in methanol as described.
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44
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84918147764
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No reaction was observed between benzylamine and the 2-alkenylthiazole 10a in methanol after 48 hours at room temperature.
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45
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84918147763
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Because of the various manipulations of the reaction mixture, it is very likely that the actual diastereoselectivity is higher than the quoted value.
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46
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84918180280
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It is worth pointing out that the stereochemical aspects of the nucleophilic conjugate addition to chiral α, β-unsaturated compounds activated by an electron-withdrawing group, is a rather complex and intriguing matter. Syn- and anti-selectivity may depend upon several factors including : i, the olefin geometry; ii) the nature and position of the asymmetric centre(s); iii) the nature of the activating group; iv) the type of nucleophile. See for instance ref. 15e and 16. See also
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(1989)
J.C.S. Chem. Commun.
, pp. 91
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Larcheveque1
Tamagnau2
Petit3
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48
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37049112080
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Asymmetric synthesis. Part 6. Copper salt promoted grignard reagent additions to ethyl 2,3-dideoxy-4,5:6,7-di-O-isopropylidene-D-arabino-trans-hept-2-enonate and subsequent formation of optically active 2-alkyl (or aryl) butane-1,4-dioic acids and butyro-1,4-lactones
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(1983)
Journal of the Chemical Society, Perkin Transactions 1
, pp. 2629
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Lawston1
Inch2
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50
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49949128203
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Torsional strain involving partial bonds. The stereochemistry of the lithium aluminium hydride reduction of some simple open-chain ketones
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(1968)
Tetrahedron Letters
, pp. 2199
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Cherest1
Felkin2
Prudent3
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56
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0001232768
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For an excellent review on the synthesis of these amino sugars, see ref. 10b. For recent papers see ref. 11f and :
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(1985)
J. Am. Chem. Soc.
, vol.107
, pp. 1269
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Danishefsky1
Maring2
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65
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84918147761
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For the synthesis of lincosamine see ref. 13d and references cited therein.
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