121923-96-4Relevant articles and documents
Total synthesis of chlorinated oxylipin eiseniachloride B
Ota, Koichiro,Kamaike, Kazuo,Miyaoka, Hiroaki
, p. 590 - 594 (2021/06/06)
Eiseniachloride B is a marine chlorinated oxylipin isolated from the brown alga Eisenia bicyclis. This natural product contains cyclopentane, chlorohydrin, and 14-membered lactone systems that incorporate five stereogenic centers. In this paper, we report on the total synthesis of structurally unique oxylipin eiseniachloride B from optically active lactol via ecklonialactone B in a linear sequence comprising 11 steps with a 12.1% overall yield.
Catalytic asymmetric claisen rearrangement of gosteli-type allyl vinyl ethers: Total synthesis of (-)-9,10-dihydroecklonialactone B
Becker, Julia,Butt, Lena,Von Kiedrowski, Valeska,Mischler, Elisabeth,Quentin, Florian,Hiersemann, Martin
supporting information, p. 3040 - 3051 (2014/05/06)
The enantioselective synthesis of (-)-9,10-dihydroecklonialactone B is described. The catalytic asymmetric Claisen rearrangement of a Gosteli-type allyl vinyl ether was utilized to afford an acyclic α-keto ester building block endowed with functionality a
Total synthesis of (-)-ecklonialactone B
Becker, Julia,Butt, Lena,Von Kiedrowski, Valeska,Mischler, Elisabeth,Quentin, Florian,Hiersemann, Martin
, p. 5982 - 5985 (2014/01/06)
The total synthesis of (-)-ecklonialactone B as well as the 9,10-dihydro derivative by two different strategies is reported. The catalytic asymmetric Claisen rearrangement of Gosteli-type allyl vinyl ethers delivered elaborated α-keto ester building blocks. Ring-closing metatheses, including a notable diastereotopos-differentiating variant, a B-alkyl Suzuki-Miyaura cross-coupling reaction and a regio- and diastereoselective last-step epoxidation are key contributors.
Catalysis-based and protecting-group-free total syntheses of the marine oxylipins hybridalactone and the ecklonialactones A, B, and C
Hickmann, Volker,Kondoh, Azusa,Gabor, Barbara,Alcarazo, Manuel,Fuerstner, Alois
, p. 13471 - 13480 (2011/10/10)
Concise and protecting-group-free total syntheses of the marine oxylipins hybridalactone (1) and three members of the ecklonialactone family (2-4) were developed. They deliver these targets in optically pure form in 14 or 13 steps, respectively, in the longest linear sequence; five of these steps are metal-catalyzed and four others are metal-mediated. The route to either 1 or 2-4 diverges from the common building block 22, which is accessible in 7 steps from 2[5H]furanone by recourse to a rhodium-catalyzed asymmetric 1,4-addition reaction controlled by the carvone-derived diene ligand 35 and a ring-closing alkene metathesis (RCM) catalyzed by the ruthenium indenylidene complex 17 as the key operations. Alternatively, 22 can be made in 10 steps from furfural via a diastereoselective three-component coupling process. The further elaboration of 22 into hybridalactone as the structurally most complex target with seven contiguous chiral centers was based upon a sequence of cyclopropanation followed by a vanadium-catalyzed epoxidation, both of which were directed by the same free hydroxy group at C15. The macrocyclic scaffold was annulated to the headgroup by means of a ring-closing alkyne metathesis reaction (RCAM). In response to the unusually high propensity of the oxirane of the targeted oxylipins for ring opening, this transformation had to be performed with complexes of the type [(Ar3SiO)4Mo≡CPh] [K·OEt2] (43), which represent a new generation of exceedingly tolerant yet remarkably efficient catalysts. Their ancillary triarylsilanolate ligands temper the Lewis acidity of the molybdenum center but are not sufficiently nucleophilic to engage in the opening of the fragile epoxide ring. A final semireduction of the cycloalkyne formed in the RCAM step to the required (Z)-alkene completed the total synthesis of (-)-1. The fact that the route from the common fragment 22 to the ecklonialactones could follow a similar logic showcased the flexibility inherent to the chosen approach.
Protecting-group-free and catalysis-based total synthesis of the ecklonialactones
Hickmann, Volker,Alcarazo, Manuel,Fuerstner, Alois
supporting information; experimental part, p. 11042 - 11044 (2010/10/02)
A concise and protecting-group-free total synthesis of optically pure ecklonialactones A (1) and B (2) is described. The successful route to these oxylipins isolated from various brown algae involves five transition-metal- catalyzed transformations in the longest linear sequence of 13 steps. The first chiral center was set by a rhodium-catalyzed 1,4-addition of an alkenyl boronate to the commercial butenolide 11, which was controlled by Carreira's carvone-derived diene ligand 21. Other key steps involve a ring-closing olefin metathesis effected by the ruthenium indenylidene complex 22 for the formation of the five-membered carbocycle, a vanadium-catalyzed, hydroxy-directed epoxidation, and a ring-closing alkyne metathesis (RCAM) to forge the macrocyclic ring. Because of the unusually high propensity of the oxirane of the ecklonialactones for ring-opening, this transformation was best achieved with [(Ph3SiO)3MoξCPh]>=OEt2 (34) as the catalyst, which is a representative of a new generation of highly tolerant yet remarkably efficient molybdenum alkylidyne complexes. The ancillary triphenylsilanolate ligands in 34 temper the Lewis acidity of the molybdenum center and are not able to nucleophilically open the fragile epoxide ring. The final reduction of the cycloalkyne formed in the RCAM step to the required (Z)-alkene was accomplished either by Lindlar reduction or with the aid of nickel boride.
