Functionalization of GlucoPyranosides at position 5 by 1,5 C–H insertion of Rh(II)-Carbenes: Dramatic influence of the anomeric configuration

Emerging Organometallic Methods for the Synthesis of C‐Branched (Hetero)aryl, Alkenyl, and Alkyl Glycosides: C−H Functionalization and Dual Photoredox Approaches

“… Nondirected C(sp 3 )−H quaternization of position 5 on glycopyranosides reported by Lecourt et al [69] …”

“…applied this methodology to access C‐branched glucopyranoses, quaternized in position 5 (Scheme 34). [69] Through the same strategy, they placed the diazoacetate functionality on position 6. They revealed that the choice of protecting groups for positions 2–4 was crucial both to avoid side reactions and to deactivate the undesired adjacent C−H bonds.…”

Recent advances in transition-metal-catalyzed carbene insertion to C–H bonds

“…161 Rh(II)-catalyzed carbene insertion to the anomeric C-H bonds of carbohydrates has been reported to access ketopyranosides and derivatives. [162][163][164][165] Due to the presence of multiple functional groups in a carbohydrate molecule, its further functionalization becomes very difficult. In general, modification of a sugar (carbohydrate) backbone requires a multistep and time-consuming approach involving: (a) selective protection/deprotection of a specific position; (b) oxidation of the resultant alcohol; (c) addition of an organometallic reagent.…”

“…These results have demonstrated a promising potential for the synthesis of natural products and other organic compounds using hollow fibers. (165) A cascade reaction strategy was developed by using a microfluidic flow reactor system containing immobilized dirhodium complex catalyst in conjunction with the flow synthesis of diazo compounds from a-ketoesters at room temperature (Scheme 146). 477 In the reactor system, the first column is filled with poly(styrene)-supported NIK resin (PS-SO 2 NIK), where relatively stable hydrazones were converted to the corresponding diazo compounds.…”