Stereoselective synthesis of 1,2-annulated-C-Aryl glycosides from carbohydrate-derived terminally unsubstituted dienes and arynes: Application towards synthesis of sugar-fused- or branched- naphthalenes, and C-Aryl glycosides

o-Silylaryl Triflates: A Journey of Kobayashi Aryne Precursors

“…Subsequently, the same group applied Oppolzer’s sultam as the chiral auxiliary in diastereoselective Diels–Alder reactions between either the pyrrole or furan moiety and o -silylaryl triflates, affording enantiomerically pure benzofused [2.2.1] heterobicycles . Moreover, aryne Diels–Alder reactions with linear dienes were then utilized by various groups. − It is worth mentioning that Vankar and co-workers applied this strategy in the preparation of 1,2-annulated- C -aryl glycosides 4-16 from 1,3-diene 4-15 , the products of which could be further converted to sugar-fused and sugar-branched naphthalenes as well (Scheme b) …”

“…214−223 It is worth mentioning that Vankar and co-workers applied this strategy in the preparation of 1,2-annulated-C-aryl glycosides 4-16 from 1,3diene 4-15, the products of which could be further converted to sugar-fused and sugar-branched naphthalenes as well (Scheme 18b). 224 In some cases, the cycloadducts could undergo eliminative aromatization to assemble naphthalene rings. In 2003, Comins et al demonstrated that a tandem [4 + 2] cycloaddition reaction between arynes and 5-vinyl-2,3-dihydro-4-pyridones (4-17) with a following eliminative aromatization could afford β-amino-ketones 4-18 (Scheme 19a).…”

Electrochemical Bromination of Glycals

“…To demonstrate the potential applicability of 2-bromoglycals, the reaction of 2-bromogalactal 3h with different substrates was carried out ( Scheme 2 ). First, we explored the utility of 2-bromogalactal 3h in the synthesis of 2C-substituted carbohydrates, which exist in many natural products ( Yin and Linker, 2012 ; Dubbu et al, 2018 ; Darbem et al, 2020 ). Compound 3h reacted with phenylacetylene 4a in the presence of Pd(PPh 3 ) 2 Cl 2 , CuI and Et 3 N to afford the coupled product 5a in 80% yield ( Koester and Werz, 2012 ).…”

Carbohydrate‐Derived Dienes as Building Blocks for Pharmaceutically Relevant Molecules

“…In an expansion of the DA scope to benzynederived dienophiles, galactose and glucose-based dienes were transformed into a wide spectrum of 1,2annulated C-aryl glycosides as shown in Scheme 11. [38] For example, the treatment of dienes 60 with various benzyne precursors 61 provided a library of annulated C-aryl-glycosides 62. These could be further derivatized to form diverse scaffolds of interest, such as 1,2sugar fused-naphthalenes (!63; through DDQ), acyclic sugar derivatized-naphthalenes (!64; through KF and high temperature), dihydroxylated derivatives (!65; through OsO 4 /NMO), and 1,2-annulated-C-aryl glucosides (!66; NaIO 4 -based cleavage of dihydroxylated product).…”