Syntheses of deoxy oligosaccharides

The Tandem Ring‐Closing Metathesis–Isomerization Approach to 6‐Deoxyglycals

“…The resulting alcohol 6 was protected as TBS ether 7, which gave, under tandem RCM-isomerization conditions, a ring expanded l-rhodinal analogue 8 (Scheme 2). Evidence for the assigned relative configuration of 8 comes, in analogy to protected l-rhodinals 5, from the small l-Amicetal and its ring-expanded analogue: As mentioned above, a route to the l-amicetal series starting from ethyl lactate is also feasible: silylation of 1 gives TBS-protected ethyl lactate (9). Reduction of 9 with DIBAL-H to the corresponding lactaldehyde [48] and subsequent addition of vinyl magnesium chloride to give 10 have previously been reported.…”

“…Different glycosylation procedures were tested: with triphenyl phosphonium bromide [51] the required precursor was obtained, but only as a mixture of epimers and in extremely poor yield. Thiems iodoglycosylation method [9,52] was tested next. In spite of difficulties that may obviously arise from the presence of three different C À C double bonds, successful application of the method to glycoside formation with an allylic alcohol has been reported in the literature.…”

“…[8] For the assembly of oligosaccharide chains and their connection to aglycons by chemical means glycals have evolved as particularly useful building blocks. [9][10][11][12] The term glycal, introduced in the literature by Fischer and Zach in their original contribution [13] to describe the chemical resemblance of these compounds to aldehydes, is nowadays used for 1,2-unsaturated sugars. Due to their enol ether structure, they show interesting reactivities that have proven useful in target molecule synthesis, beyond carbohydrate chemistry.…”

Synthesis of 3‐Deoxy Glycals via Tandem Metathesis Sequences and Their Use in an Intermolecular Heck Arylation

“…[1] In particular, deoxygenated carbohydrates have attracted considerable attention for many years, both from the biochemical [2] and the synthetic [3] point of view. For instance, deoxy carbohydrates are frequently found as constituents of oligosaccharide side chains in antibiotics, [4] and incorporation of novel substitution and deoxygenation patterns might help to overcome resistance of certain pathogenic bacteria to these antibiotics.…”

Glycosidase-catalyzed Deoxy Oligosaccharide Synthesis. Practical Synthesis of Monodeoxy Analogs of Ethyl β-Thioisomaltoside UsingAspergillus nigerα-Glucosidase

“…Synthetic aspects of the chemical construction of 2-deoxyglycosides have been recently reviewed. [1][2][3][4] In chemical glycosylation, the OH-2 group of the donor sugar plays an important role in the anomer selectivity. Moreover, the OH-2 group of the glycon moiety of the synthesized glycoside has also been shown to contribute to the stability of its glycosidic linkage.…”