137410-35-6

Upstream product

• 137410-33-4 3,5,8-Trimethoxy-1-methyl-9,10-dioxo-9,10-dihydro-anthracene-2-carboxylic acid ethyl ester 
• 137410-34-5 ethyl 1-methyl-3,5,8,9,10-pentamethoxyl-2-anthracene carboxylate 
• 125343-69-3 2,3,4,6-tetra-O-benzyl-1-O-(trifluoroacetyl)-α-D-glucopyranose 
• 129889-18-5 2,3,4,6-Tetra-O-benzyl-β-D-glucopyranosyl trifluoroacetate 

Downstream Products

• 137410-38-9 3,5,8-Trimethoxy-1-methyl-9,10-dioxo-7-((2S,3S,4R,5R,6R)-3,4,5-tris-benzyloxy-6-benzyloxymethyl-tetrahydro-pyran-2-yl)-9,10-dihydro-anthracene-2-carboxylic acid ethyl ester 

Relevant academic research and scientific papers

The First Total Synthesis of Carminic Acid

The first synthesis of carminic acid (7β-D-glucopyranosyl-1-methyl-3,5,6,8-tetrahydroxy-9,10-anthraquinone-2-carboxylic acid), was accomplished by direct C-glucosylation of ethyl 3,5,8,9,10-pentamethoxy-1-methylanthracene-2-carboxylate, here synthesized, which affords ethyl 7-(2,3,4,6-tetra-O-benzyl-β-D-glucopyranosyl)-3,5,8,9,10-pentamethoxy-1-methylanthracene-2-carboxylate and carminic acid by regeneration of the masked functionalities.

Synthesis of carminic acid, the colourant principle of cochineal

The first synthesis of carminic acid (7β-D-glucopyranosyl-3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-9,10- dihydroanthracene-2-carboxylic acid) is described. Selective C-glycosylation at the 7-position of ethyl and benzyl 3,5,8,9,10-pentamethoxy-1-methylanthracene-2-carboxylates with 2,3,4,6-tetra-O-benzyl-1-trifluoroacetyl-α-D-glucopyranose afforded intermediates which were oxidised to ethyl and benzyl 3,5,8-trimethoxy-1-methyl-9,10-dioxo-7-(2′,3′,4′,6′- tetra-O-benzyl-β-D-glucopyranosyl)-9,10-dihydroanthracene-2-carboxylate respectively. The benzyl compound was hydrogenolysed and the ethyl analogue hydrogenolysed and hydrolysed to give the same product, which was tetraacetylated and demethylated to afford 6-deoxycarminic acid tetraacetate, 3,5,8-trihydroxy-1-methyl-9,10-dioxo-7-(2′,3′,4′,6′- tetra-O-acetyl-β-D-glucopyranosyl)-9,10-dihydroanthracene-2-carboxylic acid. The pentamethoxy intermediates were obtained from 2-chloronaphthazarin by Diels-Alder addition to 3-alkoxycarbonyl-2,4-bis(trimethylsiloxy)penta-2,4-dienes to give alkyl 6-deoxykermesates. Methylation afforded the corresponding trimethyl ethers, which by reductive methylation gave the required pentamethoxy compounds. By known steps 6-deoxycarminic acid tetraacetate was converted into the 5,8,9,10-bisquinone, acetoxylation of which gave carminic acid octaacetate. Acidic hydrolysis afforded carminic acid.