Evolution of a Gram-Scale Synthesis of (+)-Discodermolide
作者:Amos B. Smith、Thomas J. Beauchamp、Matthew J. LaMarche、Michael D. Kaufman、Yuping Qiu、Hirokazu Arimoto、David R. Jones、Kaoru Kobayashi
DOI:10.1021/ja0015287
日期:2000.9.1
stereocontrolled total synthesis of the potent antimitotic agent (+)-discodermolide (1) has been achieved on gram scale. Key elements of the successful strategy include (1) elaboration of three advanced fragments from a common precursor (CP) which embodies the repeating stereochemical triad of the discodermolide backbone, (2) σ-bond installation of the Z trisubstituted olefin, exploiting a modifiedNegishi cross-coupling
followed by bromine–iodine exchange and Pd–Cu co-catalyzed Stille cross-coupling of the resulting alkenyl iodide with methyl (Z)-2-tributylstannyl-3-methoxyacrylate (7). The synthetic strobilurins G, M, and N were identical with the corresponding natural compounds. In addition, the (2′ S)-configuration of strobilurin G (1) was unambiguously established by oxidative degradation of the synthetic intermediate
The totalsyntheses of both natural (+)-spiculoic acid A and (+)-zyggomphic acid, new cytotoxic marine natural products of polyketide origin, have been accomplished for the first time. These syntheses were achieved by the highlystereoselective and high-yielding intramolecular Diels–Alder reaction of a functionalized (E,E,E)-2,7,9-dodecanal derivative to construct the core tetrahydroindan-2-one skeleton
The nickel-catalyzed intramolecularcycloaddition of dienes with unactivatable alkynes is found to proceed under mild conditions while the corresponding Diels-Alder cycloaddition of the same substrates either fails or occurs only under forcing conditions. The nickel-catalyzed cycloaddition is also shown to occur with retention of stereochemistry and is not significantly influenced by electronic effects