Conversion of Lactose into Mimics ofN-Acetyllactosamine

Abstract

The α‐C‐Glycoside of N‐acetyllactosamine 8was synthesised from lactose by acetylation, conversion into the allyl α‐C‐glycoside 4, exchanging the protecting groups for benzyl ethers, selective deprotection at the gluco‐C‐2 by iodocyclisation‐reductive elimination, and conversion of the free hydroxyl group into an acetamido group by oxidation, oximation, stereoselective reduction and acetylation. Isomerization of the C‐glycosidic appendage by conversion into a 2‐oxypropyl group and treatment with base gave, after acetylation, the β‐C‐glycoside of N‐acetyllactosamine 11.

Synthesis and Conformational Analysis of Galactose‐Derived Bicyclic Scaffolds

“…Iodocyclization of compound 4 provided a 2.6:1 inseparable mixture of diastereomeric iodides 5, [8,9] which was then submitted for azide displacement to afford the bicyclic azides 6. Hydrogenation of this mixture, over 20 % Pd(OH) 2 /C in methanol and in the presence of acetic anhydride at atmospheric pressure, afforded a mixture of the bicyclic acetamides 1 and 2, which were separated by HPLC using a Waters high performance carbohydrate 60 Å column.…”

Stereocontrolled Access to Higher Sugars (Non-1-en-4-ulopyranosyl Derivatives) and Glycomimetics [3-(β-D-Glycopyranosyl)-1-propenes and(3Z)-4,8-Anhydro-nona-1,3-dienitols]

“…-gluco, [13,16] -manno, [16,17] -galacto, [16,18Ϫ20] lactose, [16,20,21] -ribo (BF 3 ·OEt 2 , TMSOTf, ZnBr 2 ), [22Ϫ24] and other [16,23Ϫ25] ], benzoyloxy, [23,24,26] 2,4,6-trimethylbenzoyloxy, [16] 4-nitrobenzoyloxy, [7,24] nitrate, [27] bromide, [13] chloride, [10,12] and fluoride. [28] 3-Glycosyl-1-propenes could also be prepared using allyltrimethylsilane by Lewis acid-catalyzed opening of anhydro sugars (1,2-, [9] 1,4-, [29] and 1,6-anhydro sugars [7] ) of radical-mediated allylation of 1؊3, [59,60] we found it preferable to resort to photolytic conditions, where the temperature of the reaction mixture was maintained below ca.…”