Massadine Chloride: A Biosynthetic Precursor of Massadine and Stylissadine

Abstract

In this Communication, the structure of compounds 3 and 5 was incorrectly drawn. The correct structure is shown below. The editorial office apologizes for this oversight.

Lessons and revelations from biomimetic syntheses

“…Indeed, the pathway from one to the other may not be simple, but by postulating the biosynthetic relationships, a viable intermediate that may be a natural product in its own right can be identified. For example, when massadine chloride was isolated 52 , it had previously been predicted as a key biosynthetic intermediate in the synthesis of the pyrrole-imidazole alkaloid family of natural products (as described below) 53 In three consecutive reports published in 2007, the structures of notoamides A-D (isolated from the marine fungus Aspergillus sp.,) were revealed, along with the biomimetic syntheses of notoamides B-D [54][55][56] . Subsequently, the structures of up to 20 members of this family-derived from isoprene, tryptophan and proline (Fig.…”

“…Another recent example of natural product discovery is exiguamine B (52). Exiguamine A (50), first isolated from the marine sponge Neopetrosia exigua, is a hexacyclic alkaloid and the most potent inhibitor of the enzyme indoleamine 2,3-dioxygenase (IDO) known 71 .…”

Total Synthesis of Palau’amine

“…Substitution of the secondary hydroxyl group with chloride with stereoretention proceeded by exploiting a neighboring group effect with the guanidine containing F ring. Secondary alcohol activation using sulfuryl chloride induced the participation of guanidine depicted in 33 analogous to massadine aziridine , 18 and subsequent nucleophilic attack of chloride afforded 34 with the α con guration of chloride, along with a small amount of the epimer at the C20 position in the unnatural con guration. On the other hand, the hemiaminal hydroxyl group also reacted with excess sulfuryl chloride to give a dichloride when more than 1.0 equiv of sulfuryl chloride was used, but the chloride at the C20 position was readily hydrolyzed back to 34 in THF H 2 O at 50 .…”

Dimeric pyrrole–imidazole alkaloids: synthetic approaches and biosynthetic hypotheses

“…31,40 Cyclization of 14 would afford massadine chloride ( 6b ), axenellamines ( 7 ), and konbu’acidins ( 8b,c ). While massadine ( 6a ) and massadine chloride ( 6b ) could be produced independently, Köck and Baran showed that 6a could be converted to 6b completely by incubating 6a in water at 60 °C for 4 h. 40 The retention of stereochemistry could be explained by an aziridinium intermediate that was previously proposed by Romo. 19d …”