Glycosidation Reactions of Silyl Ethers with Conformationally Inverted Donors Derived from Glucuronic Acid: Stereoselective Synthesis of Glycosides and 2‐Deoxyglycosides

Abstract

Stereoselective glycoside synthesis is of interest because of the biological and medical relevance of oligosaccharides, glycoproteins, glycolipids, [1] and other carbohydrate derivatives, [2] and a range of strategies have been developed to produce these compounds.[3] The 1,6-lactone derivative 2 (see Scheme 1) has potential for use in the synthesis of 1,2-cisglycosides [4] but its application has been limited because of the low yields obtained from its reaction with alcohols.[5] We now report that the SnCl 4 -catalyzed coupling of silyl ethers [6] with 2 provides a-O-glucuronides in significantly improved yields without loss of stereoselectivity. The methodology has been extended to the related 2-deoxylactones, which give aor b-glycosides depending on the structure of the donor.The preparation of 2 was carried out via the mixed anhydride 1 (Scheme 1) by an improved and shorter procedure than that previously described.[5] The donors 6 and 7 were also prepared, via glycal 4, because of their potential for the synthesis of 2-deoxyglycosides, which are of biological interest.[7] Thus, the reaction of the allyl ester 3 with hydrogen bromide in acetic acid gave a glycosyl bromide intermediate

Synthesis of a-O- and a-S-Glycosphingolipids Related to Sphingomonous cell Wall Antigens Using Anomerisation

“…In this article we present a full account of work on the synthesis of α-S-, SO 2 -and O-linked glycolipids 5-10 which are based on glucuronic acid and galacturonic acid. This article supplements two preliminary communications [13,14] where we have outlined how chelation induced anomerisation [15][16][17][18] can be used for the preparation of S-and O-glycolipids relevant to biology and medicine. Herein we provide additional examples and more detail regarding our initial efforts in this area.…”

“…The precipitate was then lyophilised to give a mixture of regioisomers (3.6 mg, 52%) where the 1,4-regioisomer 10 was the major product and there was also 12% of the 1,5-regioisomer. Analytical data for the major isomer 10: (15). To a stirred solution of the β-thiol 10 34 (100 mg, 0.28 mmol) in CH 2 Cl 2 (3 mL) was added TiCl 4 (76 µL, 0.7 mmol) dropwise.…”

Selective Synthesis of Glycoside Fatty Acid Esters and Their Antibacterial Structure‐activity Relationship against Bacterial Staphylococcus Aureus and Salmonella Agona

“…However, the a configuration of glucuronide, which is possibly to be regioselectively acylated with stannylene method, need to be stereoselectively synthesized from glucuronic acid. Many methods were documented to convert glucuronic acid into a-D-glucuronides, among reported methods the one by TMSR mediated ring opening of 1,6-anhydro sugars is rather effective with high selectivity, [19][20][21] as shown in Scheme 1. With this method two substrates methyl a-D-glucopyranosiduronide and azido a-D-gluco pyranosiduronide were prepared.…”

Metathesis and Macrocycles with Embedded Carbohydrates

“…The glycoside 3 was first prepared from the -glucuronic acid 6,1-anydro derivative 2. [14] The free acid in 3 was then converted to its acid chloride, which was then reacted with phenylene-1,4-diamine to yield the diamide. This intermediate was di-N-methylated using methyl iodide in the presence of sodium hydride in DMF to give 4.…”

“…The synthesis of 18 is shown in Scheme 3. The α-glycoside 3 [14] was treated with sodium methoxide in methanol and subsequent acetylation produced a 6,3-lac-4962 tone intermediate. This lactone was immediately reacted with allyl alcohol in the presence of molecular sieves and sodium acetate to give 21.…”