58857-02-6Relevant academic research and scientific papers
Total synthesis of (+)-ambruticin S: Probing the pharmacophoric subunit
Hanessian, Stephen,Focken, Thilo,Mi, Xueling,Oza, Rupal,Chen, Bin,Ritson, Dougal,Beaudegnies, Renaud
experimental part, p. 5601 - 5618 (2010/11/03)
An enantioselective synthesis of the antifungal natural product (+)-ambruticin S has been accomplished starting with the readily available methyl α-d-glucopyranoside, (R)-Roche ester, and (S)-glycidol as chirons, which encompassed seven of the 10 stereogenic centers of the target molecule. The remaining three centers were set by a highly diastereoselective, asymmetric cyclopropanation employing a chiral, nonracemic phosphonamide reagent. Our strategy for the construction of the dihydropyran subunit involved a highly syn-selective Lewis acid catalyzed 6-endo-trig cyclization. Other key steps in the synthesis featured an epoxide opening with a dithiane anion, two efficient phosphonamide-anion based olefinations, and a late-stage C-glycosylation.
Total synthesis of (+)-ambruticin S
Berberich, Stephen M.,Cherney, Robert J.,Colucci, John,Courillon, Christine,Geraci, Leo S.,Kirkland, Thomas A.,Marx, Matthew A.,Schneider, Matthias F.,Martin, Stephen F.
, p. 6819 - 6832 (2007/10/03)
A convergent total synthesis of the novel antifungal agent ambruticin S (1) has been completed from the assembly of intermediates 18, 33 and 52 that served as the respective A-, B-, and C-ring precursors. The first generation approach to a potential A-ring intermediate eventuated in the synthesis of 9a via a route that featured oxidation of the dihydroxy furan 2 and elaboration of the dihydropyranone 3 derived therefrom. Although 9a served as a precursor of 31E to complete a formal synthesis of 1, there were several inefficiencies associated with the preparation of 9a. A more expedient and efficient route to an A-ring subunit was devised that commenced with the carbohydrate-derived bisacetonide aldehyde 10 and produced 18 in five steps and 46% overall yield. The synthesis of the cyclopropyl sulfone 33 was initiated with the enantioselective cyclopropanation of 19 catalyzed by Rh 2[5(S)-MEPY]4. Ring opening of the resultant lactone 20 followed by a series of refunctionalizations gave 33 in a total of seven steps and 46% yield from 19. Coupling of the A- and B-ring precursors 18 and 33 was then achieved via a modified Julia coupling followed by deprotection and oxidation to furnish the key intermediate 35. The dihydropyran core of the C-ring subunit precursor 49 was formed from the ring closing metathesis of the diene 48, which was prepared in three steps from the known epoxide 45, followed by oxidation. A chelation-controlled addition to the methyl ketone 49 set the stage for a stereoselective [2,3]-Wittig rearrangement that delivered the alcohol 51 that was then transformed in two steps to the sulfone 52. A traditional Julia coupling of 52 and 35 proceeded with excellent stereoselectivity, and subsequent removal of the various protecting groups gave ambruticin S (1). The longest linear sequence was 13 steps and proceeded in 4. 3% overall yield.
Total synthesis of natural (+)-ambruticin
Kende, Andrew S.,Mendoza, Jose S.,Fujii, Yasuhiro
, p. 8015 - 8038 (2007/10/02)
The structurally unique antifungal antibiotic ambruticin (1) has been prepared for the first time in a convergent synthesis. The strategy for its synthesis involved the independent preparation of the enantiomerically pure fragments 19, 31 and 49. The required C(7) - C(8) β-C-glycoside bond was formed by coupling the glycosyl fluoride 19 with the in situ formed vinyl alane derivative 32. Formation of the C(13) - C(14) trans double bond was accomplished by condensation of the sulfone fragment 49 with the aldehyde intermediate 35 leading to the complete skeletal framework of ambruticin. Saponification of 51 and then cleavage of the benzyl protecting groups gave natural ambruticin.
