Total Synthesis of Angucyclines. XVII. First Synthesis of Antibiotic 100‐1, a Deoxydisaccharide Angucycline Antibiotic of the Urdamycinone B‐Type

Abstract

Two routes to the deoxydisaccharide angucycline antibiotic 100-1 (3) are described. Key steps comprise the regioselective oxidation/bromination of the 1,5-diacetoxyolivose C-saccharide 7 to the bromoquinone 8. Diels -Alder reaction of the bromoquinone with the diene 9 followed by HBr elimination afforded the urdamycinone B precursor 11 as a diastereomeric mixture. Selective protection as the TBDMS ether 13, acetylation and deprotection of the silyl ether afforded the alcohol 15 which was selectively glycosylated to the a-rhamnal glycoside 17 in 72% yield (at 70% conversion) using benzoyl rhamnal (16) as the glycoside donor and scandium triflate as the promotor. The silyl group at C-3 of the aglycone was then transformed into a hydroxyl group. Zemplén deacylation and photooxidation of the benzylic position at C-1 then converted the two diastereoisomers into the natural product 3 and the C-3 diastereoisomer 20. At this stage the diastereomers 3 and 20 were separated. Alternatively and more easily, the diastereomers were separated at the stage of the urdamycinone B analogues 21a and 21b, followed by a similar reaction sequence to the natural disaccharide 3.

Enzymatic Total Synthesis of Rabelomycin, an Angucycline Group Antibiotic

“…Many of the biologically active angucycline group antibiotics, including rabelomycin ( 5 ), have attracted synthetic chemists, and 5 along with other angucyclinones became model compounds for the development of efficient, synthetic routes toward this class of compounds 2,7–10. Most of these procedures require multistep chemical transformations, which are often relatively tedious and time-consuming and suffer from overall low production yield.…”

OC022: Quality control in the measurement of nuchal translucency in the first trimester of pregnancy

“…17 Up to date, the effect of the sulfoxide at C‐3 in juglone derivative 6 , was unknown. The structure of tetracyclic compound 24 , resulting from the reaction between diene 4 and sulfinyl quinone 5 , was a consequence of the initial formation of the not isolated ortho ‐adduct 25 (Scheme 7); its regiochemistry was as expected taking into account the 1,2‐disubstitution of the butadiene derivative 4 5e, f and the above considerations on dienophile 5 . This is in sharp contrast to the moderate regioselectivitity reported for cycloadditions of 2‐ p ‐tolylsulfinyl juglone acetate 36a…”

Palladium-catalyzed C–H glycosylation and retro Diels–Alder tandem reaction via structurally modified norbornadienes (smNBDs)

“…Notably, C-aryl glucoside skeleton has high biological metabolism stability, which has been widely found in nature, and C-glycosyl indole derivatives have unique biological activities widely used in the field of medicinal chemistry. [4][5][6][7][8][9][10][11][12][13][14] In 1994, the Hofsteenge group first discovered α-C-Mannosyltryptophan (α-C-Man-Trp) I from the Trp7 of ribonuclease. [15][16][17] Due to its unique structure and biological activities such as cellular signalling and communication, these compounds have attracted considerable attention.…”