Stereoselective glycosylation of endo-glycals by microwave- and AlCl3-assisted catalysis

Recent Developments in the Ferrier Rearrangement

“…Lin et al described the formation of α‐2‐deoxyglycosides by microwave‐ and AlCl 3 ‐assisted (50 °C, microwave irradiation, cyclohexanol as nucleophile) glycosylations with 4,6‐di‐ O ‐benzyl‐ D ‐galactal derivatives 96. After a preliminary screening on the effect of different Lewis acids (0.2 equiv.)…”

α‐Selective Organocatalytic Synthesis of 2‐Deoxygalactosides

“…[9] Catalyzing the direct addition of an alcohol to a glycal (2) is the most atom-efficient route to 2-deoxyglycosides. [10] Existing methods (Scheme 1 a) tend to be mostly confined to primary alcohol acceptors and give either moderate yields or variable selectivities. [10] Herein, we describe a highly atom-efficient method for the direct reaction of readily available galactals with alcohols to give alinkages with high stereoselectivity using an organocatalyst.…”

“…Glycosylation reactions involving glycals tend to give better stereoselectivities under mild conditions. [10] Organocatalysts often work under such conditions and tend to be more tolerant of sensitive functional groups. [11,12] Recently, Kotke and Schreiner reported the use of thiourea 1 to catalyze the protection of alcohols with dihydropyran (DHP) under mild conditions (Scheme 1 b).…”

“…Catalytic acetal formation from enol ethers. [10,13] Encouraged by these results, the scope of other common glycosyl acceptors was investigated ( Table 2). To that end, perbenzylated galactal 2 d was used as a model donor and reacted with a range of differentially protected glycosyl acceptors 3 b-3 j under the optimized reaction conditions.…”

O-Glicosídeos 2,3-Insaturados: Aplicações, Rearranjo De Ferrier E Reações

“…97 Vale destacar que a irradiação de micro-ondas para o rearranjo de Ferrier vem sendo relatada na literatura. 98 Em 2011, Lin et al 99 utilizaram a irradiação de micro-ondas para promover a síntese de α-O-2-deoxiglicosídeo. Neste trabalho, os autores discutiram alguns pontos sobre a reação de glicosilação, tais como os efeitos dos ácidos de Lewis, do nucleófílo, da irradiação de micro-ondas e o estudo mecanístico na seletividade de endo-glical.…”