167167-28-4Relevant academic research and scientific papers
Production of anticancer polyenes through precursor-directed biosynthesis
Clark, Benjamin R.,O'Connor, Stephen,Fox, Deirdre,Leroy, Jacques,Murphy, Cormac D.
experimental part, p. 6306 - 6311 (2011/10/10)
The biosynthesis of the pyrrolyl moiety of the fungal metabolite rumbrin originates from pyrrole-2-carboxylic acid. In an effort to produce novel derivatives with enhanced biological activity a series of substituted pyrrole-2-carboxylates were synthesised
Preparation of alkyl-substituted indoles in the benzene portion. Part 15. Asymmetric synthesis of (+)-duocarmycin SA using novel procedure for preparation of hydroxyindoles
Muratake, Hideaki,Matsumura, Naoshige,Natsume, Mitsutaka
, p. 559 - 571 (2007/10/03)
An asymmetric total synthesis of natural (+)-duocarmycin SA (1) starting from L-malic acid (7) was achieved as shown in Chart 5, establishing firmly the absolute configuration of 1. In order to find suitable reaction conditions for the key step, i.e., the formation of an alkoxyindole derivative, model compounds 9 and 40 were synthesized and two acetalization conditions using i) 2-ethyl-2-methyl-1,3-dioxane and boron trifluoride etherate, and ii) 1,3-bis(trimethylsilyloxy)propane and trimethylsilyl trifiate were found to be effective. The former conditions were successfully applied to the total synthesis and 49b was prepared from 48 in 54% yield. Further elaborations including i) Curtius rearrangement of 53b to 56, and it) cleavage of the primary benzyloxy group in the presence of the secondary one in its close vicinity (56→57) led to the relay compound 62, whose conversion to 1 has already been accomplished.
Synthesis of duocarmycin SA by way of methyl 4-(Methoxycarbonyl)oxy-3H- pyrrolo[3,2-f]quinoline-2-carboxylate as a tricyclic heteroaromatic intermediate
Muratake, Hideaki,Tonegawa, Miyuki,Natsume, Mitsutaka
, p. 400 - 412 (2007/10/03)
Formal syntheses of (±)-duocarmycin SA, natural (+)-duocarmycin SA and unnatural (-)-duocarmycin SA were accomplished by way of a tricyclic heteroaromatic compound 10b. For the preparation of 10, an N-oxide route aiming at a process 20 in Chart 3 was first investigated by synthesizing 19, derived from Stille coupling products 13 between bromopyrrole 7a and 3- (tributylstannyl)pyridines 12, but without success. As the second approach, Stille coupling products 9a-c were prepared by condensation between 7a and 2- substituted 3-(trialkylstannyl)pyridines 8a-f. Both 9b and 35, derived from 9c, were converted to their silyl enol ethers and then subjected to a palladium-catalyzed methyl ketone-arylation reaction in the presence of tributyltin fluoride and lithium chloride, affording 10a and 10b in excellent yields, especially from 35. Application to 10b of three successive operations, i.e., i) partial reduction of 10b to dihydropyridine derivatives 11a and 11b, ii) dihydroxylation of the double bonds formed to give 58 and 59, and iii) reductive elimination of the hydroxy groups adjacent to the nitrogen function and the aromatic ring, afforded 6 in fairly good yield. Compound 6 was readily converted to relay compounds 64 and 67, completing total syntheses of (±)-, (+)-, and (-)-duocarmycin SA. Both Sharpless asymmetric dihydroxylation (AD) and Jacobsen's asymmetric epoxidation were applied to 11a and 11b. At the best, 81% ee was observed in the AD reaction of 11a using 2,5-diphenyl-4,6-bis(9-O-dihydroquinyl)pyrimidine [(DHQ)2PYR], but the resulting 58 possessed an unnatural absolute configuration.
