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1.
The asymmetric synthesis of the antibacterial natural product, streptophenazine G, has been achieved by employing asymmetric alkylation and asymmetric aldol reactions using chiral oxazolidinones as the key steps. The originally proposed structure for streptophenazine G has been revised, and its absolute configuration has been determined to be 1'S,2'R,6'S. The asymmetric total synthesis of 6'-epi-streptophenazine G is also described. 相似文献
2.
Raquel G. Soengas Alfonso Espada Marta Larrosa Carlos Jiménez 《Tetrahedron letters》2007,48(17):3021-3024
The stereochemistry of vanchrobactin, a siderophore produced by the bacterial fish pathogenVibrio anguillarum serotype O2, was elucidated by chiral capillary electrophoresis analysis and total synthesis as N-[N′-(2,3-dihydroxybenzoyl)-d-arginyl]-l-serine. 相似文献
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An enantioselective synthesis of the structure reported for the natural antifungal compound, (−)-crassinervic acid (1), has been achieved starting from geraniol and p-hydroxybenzoic acid. The key chirality-inducing step is a Sharpless asymmetric epoxidation of an allylic alcohol, on the basis of which the S configuration can be assigned to the (−) natural enantiomer. The discrepancies between the spectroscopic data for synthetic and natural crassinervic acid cast some doubts on the structure assigned to the natural compound. A possible revised structure is discussed. 相似文献
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Verticilide (1) is a 24-membered cyclic depsipeptide isolated from the culture broth of Verticillium sp. FKI-1033. It inhibits ryanodine binding to ryanodine receptor (RyR) and has insecticidal activity. The stereochemistry of 2-hydroxyheptanoic acid in verticilide was elucidated by chiral HPLC analysis of the degradation product 6 and synthetic (+) and (-)-6. We also describe the practical total synthesis of verticilide. [reaction: see text]. 相似文献
7.
The first total synthesis of the polyketide apiosporic acid is presented. Key steps are a Julia-Kocienski olefination, a Suzuki-Miyaura cross-coupling, and an intramolecular Diels-Alder reaction. The absolute configuration of the natural product was determined. 相似文献
8.
The first total synthesis and determination of the absolute configuration of chapecoderin A, B and C
The seco- and rearranged-labdanes, chapecoderins A 1, B 2, and C 3 have been synthesized for the first time starting from (S)-(+)-Wieland-Miescher ketone analogue 11. Their absolute configurations have been determined as depicted in the structures 1, 2 and 3. 相似文献
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Asymmetric synthesis of putaminoxin, a phytotoxic macrolide from the cultured dinoflagellate Amphidinium sp., has been accomplished. Absolute configuration of putaminoxin was concluded to be 1 from comparison of the NMR data and [α]D values of synthetic and natural putaminoxin. 相似文献
11.
The total synthesis of the reported structure 2 for yatakemycin, an exceptionally potent, naturally occurring antitumor agent disclosed in 2003, and its lack of correlation with the natural product are detailed. On the basis of spectroscopic distinctions between 2 and yatakemycin, the natural product structure was reformulated as 3, now bearing a thiomethyl ester versus thioacetate in the left-hand subunit. Total synthesis of 3 provided a compound nearly identical to but still subtly distinct from the natural product. A second reformulation of the yatakemycin structure as 1, incorporating the alternatively substituted right-hand subunit as well as the initial thiomethyl ester reformulation, was confirmed by total synthesis of both (+)- and ent-(-)-1 in studies that also unambiguously established the absolute configuration of the natural product. 相似文献
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The first total synthesis and the absolute configuration determination of varitriol are described. 相似文献
14.
Enantioselective first total synthesis of diosniponol A and B has been achieved starting from commercially available vanillin. Wittig reaction, Keck allylation, and Prins cyclization reactions are the key steps involved in the target synthesis. 相似文献
15.
Kuniaki Tatsuta Akira Nakagawa Shunji Maniwa Mitsuhiro Kinoshita 《Tetrahedron letters》1980,21(15):1479-1482
The total synthesis of a sixteen-membered macrocyclic lactone antibiotic, A26771B and its absolute configuration are described by using D-glucose as a chiral source. 相似文献
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Masako Nakagawa Hiroyuki Sugumi Shinichi Kodato Tohru Hino 《Tetrahedron letters》1981,22(52):5323-5326
First total synthesis of ditryptophenaline is described and the absolute configuration was determined. 相似文献
18.
Guo-Bao Ren 《Tetrahedron》2008,64(19):4408-4415
The title compound, one of the constituents from Iryanthera megistophylla, has been synthesized in enantiopure forms. The stereogenic centers at C-2 and C-3 were constructed by using a chiral auxiliary induced asymmetric aldolization and the C-4 was derived from the corresponding optically active lactates. The carbon-carbon double bond in the side chain was derived from a pure cis vinyl iodide using a Suzuki coupling with an alkyl borane formed in situ from the corresponding terminal alkene. A previously unknown (partial) cis to trans transformation of an isolated C-C double bond in a long alkyl chain was observed during the deprotection of TBS group with CAN. Somewhat unexpectedly, the otherwise undetectable co-presence of the trans isomer of the remote double bond in a long alkyl chain was clearly revealed in 1H and 13C NMR in the presence of a lactone ring. The present work unambiguously shows that the absolute configuration of the natural compound is the antipode of the one originally reported. Some errors in the previous 1H and 13C NMR signal assignments are also corrected. 相似文献
19.
P. Srihari B. Kumaraswamy P. Shankar V. Ravishashidhar J.S. Yadav 《Tetrahedron letters》2010,51(47):6174-6176
The stereoselective total synthesis of achaetolide 1 has been achieved and its absolute stereochemistry has been reconfirmed to be 3S,6R,7S,9R configuration. Keck allylation, Sharpless asymmetric dihydroxylation, and ring closing metathesis are the key steps involved in the target synthesis. 相似文献
20.
The first synthesis of mispyric acid (1), an inhibitor of DNA polymerase beta with a novel triterpene skeleton, was achieved by starting from isoprene (2), geraniol (6) and 1,5-dimethoxy-1,4-cyclohexadiene (14). The absolute configuration of the naturally occurring 1 was determined as 2S,4S. 相似文献