Total synthesis acetogenin

The acetogenin (+)-solamin and analogs were prepared via a ruthenium-catalyzed Alder-ene reaction/butenolide formation (Scheme 37).96 Of particular note is the ability of the ruthenium to catalyze the reaction in the presence of free hydroxyls, sulfides, and sulfones. Yields ranged from 65% for the sulfide to 88% for the sulfone. Trost has also applied this reaction to the total synthesis of (+)-ancepsenolide, which features a bis-Alder-ene reaction (Scheme 38).97... 

Laurencia nipponica (790), and the structure and absolute configuration were confirmed by total synthesis (791). This new compound is a stereoisomer of the known (3Z)-isoprelaurefucin. A Malaysian Laurencia pannosa has yielded (3Z)-chlorofucin (698) (578), and (3Z)-bromofucin (699), which is also a new C15-acetogenin, is found in a South African sea hare, Aplysia parvula (792). The (3 )-neoisoprelaurefucin (700) was found in Laurencia obtusa collected in Turkish waters (557). 

Tanaka has shown that in his synthesis of a variety of diastereomeric annonac-eous acetogenins (9, Scheme 3) the carbinol stereocenter can be generated with predictable selectivity by reagent control of either enantiomer of the chiral ligand [24], He applied this method in the total synthesis of murisolin (9, n= 1), a member of family of over 350 natural polyketides isolated from various annon-aceaes plants (Scheme 4). 

On basis of this work, we recently completed the total synthesis of five mono-THF acetogenins (Scheme 10-4), 4-deoxyannomonatacin, tonkinecin, ° (10/ )-... 

Takahashi et al. also completed the total synthesis of other two acetogenins, jimenezin ° (Scheme 10-36) and pyranicin (Scheme 10-37), and they revised... 

Total synthesis of solamin and reticulatacin, two mono-THF acetogenins, confirms their absolute configuration. 

Further proof has come through the recent total synthesis of several Annonaceous acetogenins. The first of these to be constructed was (+)-(15,16,19,20,23,24)-hexepf-uvaricin (19), an unnatural diastereomer of uvaricin (1) reported from our laboratories in 1991.27 Knowing the relative, but not the absolute, configuration among C(15)-C(24) of... 

The enantioselective total synthesis of the annonacenous acetogenin (+)-parviflorin was accomplished by T.R. Hoye and co-workers." The b/s-tetrahydrofuran backbone of the natural product was constructed using a sequential double Sharpless asymmetric epoxidation and Sharpless asymmetric dihydroxylation. The bis allylic alcohol was epoxidized using L-(+)-DET to give the essentially enantiopure bis epoxide in 87% yield. 

The total synthesis of (+)-asimicin, which belongs to the family of Annonaceous acetogenins, was completed by E. Keinan and co-workers. In order to create one of the tetrahydrofuran rings stereospecifically, an intramolecular Williamson ether synthesis was performed between a secondary alcohol and a secondary mesylate using pyridine as the base. 

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