Studies on the synthesis of safflomin-A, a yellow pigment in safflower petals: oxidation of 3-C-β-d-glucopyranosyl-5-methylphloroacetophenone

Bioactive Sesquiterpenoid and Polyacetylene Glycosides from Atractylodes lancea

“…However, these two compounds exhibited similar ECD spectra. A literature survey indicated that compounds possessing an asymmetric cyclohexadienone unit exhibit a Cotton effect (CE) at approximately 270 nm. − Further analysis of the literature revealed that this CE had a low amplitude (Δε ≈ +2.00). A simplified structure ( 3a ) was used for ECD calculations, and four optimized conformers (5 R ,7 R ; 5 S ,7 S ; 5 S ,7 R ; 5 R ,7 S ) were obtained using an MMFF94 calculation and the TDDFT method at the B3LYP/6-31G­(d) level.…”

C-Glycopyranosyl Arenes and Hetarenes: Synthetic Methods and Bioactivity Focused on Antidiabetic Potential

“…The synthesis of C-β- d -glucopyranosyl phloroacetophenone 4 , an important intermediate giving access to C -glucosyl flavonoids, was achieved by condensing d -glucose ( 1 ) with phloroacetophenone ( 2 ) in the presence of Sc­(OTf) 3 in aqueous organic media, with formation of variable amounts of the corresponding bis- C -β- d -glucosyl compound 6 ( Scheme A). , A 32% yield of 4 was obtained using scandium cation-exchanged montmorillonite . Interestingly, in the presence of Sc­(OTf) 3 , d -glucose ( 1 ) and methylphloroacetophenone ( 3 ), with a single substitution site, led to compound 5 in 65% yield . As the direct C -glycosylation of flavonoids with common sugars might offer a concise access to complex naturally occurring molecules, the coupling of d -glucose ( 1 ) and (±)-naringenin to afford compound 7 (Scheme A) has been evaluated systematically with commercially available rare-earth metal triflates M­(OTf) 3 as catalysts (M = Sc, Y, La, lanthanides, except Pm).…”

“…62 Interestingly, in the presence of Sc(OTf) 3 , D-glucose (1) and methylphloroacetophenone (3), with a single substitution site, led to compound 5 in 65% yield. 63 As the direct C-glycosylation of flavonoids with common sugars might offer a concise access to complex naturally occurring molecules, the coupling of D-glucose (1) and (±)-naringenin to afford compound 7 (Scheme 1A) has been evaluated systematically with commercially available rareearth metal triflates M(OTf) 3 as catalysts (M = Sc, Y, La, lanthanides, except Pm). The yields observed were changing from 2% to 41%, independently of the metal order in the periodic table, but revealed Pr(OTf) 3 as the most favorable catalyst.…”

Synthesis of (S)‐4‐C‐β‐D‐Glucosylquinochalcone: A Common Structure in the Yellow and Red Pigments of Safflower Petals

“…Compound 1 , which has a highly oxidized C ‐glycosylcyclohexadienone structure ( 2 ) and a chiral carbinol carbon, has not been found in any other natural products. We have been exploring strategies for the synthesis of these pigments . In the synthesis of the red pigment carthamin, the key compound 2 was prepared by C ‐glycosylation of the acetylbenzentetrol using acetobromoglucose in the presence of NaH .…”