Convergent syntheses of Le^X analogues

• An Wang,
• Jenifer Hendel and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2010, 6, No. 17, doi:10.3762/bjoc.6.17

• respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly

• efficient and convergent preparation of these three Lex analogues. Keywords: Birch reduction; convergent synthesis; desulfurization; Lewis X; Introduction Our group is involved in the design of new anti-cancer vaccines based on the Tumor Associated Carbohydrate Antigen (TACA) dimeric Lex (dimLex) [1][2][3

• conditions did not lead to the desired corresponding thiol or disulfide product but produced the hexyl glycoside 1. The mechanism proposed to explain this reductive desulfurization is shown in Scheme 4. It involves first a single electron transfer to the thioacetyl group that is followed by the cleavage of

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• desulfurization-fluorination has been disclosed by Hiyama [24][25][26][27]. When dithiocarbonates (2, xanthogenates) are exposed to a huge excess of hydrogen fluoride-pyridine and 1,3-dibromo-5,5-dimethylhydantoin, trifluoromethyl ethers form in moderate to excellent yields (Scheme 5 and Table 5). What makes this

• a chlorination/fluorination sequence. Preparation of trifluoromethyl ethers via an in situ chlorination/fluorination sequence. Preparation of trifluoromethyl ethers via chlorothionoformates. Preparation of trifluoromethyl ethers via fluoroformates. Oxidative desulfurization-fluorination toward

• trifluoromethyl ethers. Mechanism of the oxidative desulfurization-fluorination. Umemoto's O-(trifluoromethyl)dibenzofuranium salts 4 as CF3-transfer agents. Togni's approach using hypervalent iodine compounds as CF3-transfer agents. TAS OCF3 as a nucleophilic OCF3-transfer agent. Nitration of trifluoromethoxy