- Enantioselective synthesis of δ-/γ-alkoxy-β-hydroxy- α-alkyl-substituted Weinreb amides via DKR-ATH: Application to the synthesis of advanced intermediate of (-)-brevisamide
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A method of preparing stereodefined δ-/γ-alkoxy-β-hydroxy- α-alkyl-substituted Weinreb amides containing two successive hydroxyl-alkyl stereocenters has been developed. Further, this strategy coupled with organo-catalyzed asymmetric epoxidation culminates in the synthesis of a critical intermediate of (-)-brevisamide and its diastereomers.
- Kumaraswamy, Gullapalli,Narayana Murthy, Akula,Narayanarao, Vykunthapu,Vemulapalli, Sahithya Phani Babu,Bharatam, Jagadeesh
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p. 6751 - 6765
(2013/10/01)
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- Lasonolide A: Structural revision and total synthesis
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The proposed structure of lasonolide A was synthesized employing radical cyclization reactions of β-alkoxyacrylates for preparation of the tetrahydropyranyl units A and B, but the spectroscopic data did not match those of the natural product. Both enantio
- Song, Ho Young,Joo, Jung Min,Kang, Jung Won,Kim, Dae-Shik,Jung, Cheol-Kyu,Kwak, Hyo Shin,Park, Jin Hyun,Lee, Eun,Hong, Chang Yong,Jeong, ShinWu,Jeon, Kiwan
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p. 8080 - 8087
(2007/10/03)
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- A novel stereoselective route to some uncommon amino acids
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An efficient synthesis of a D-erythro-β-methylaspartic acid analog was achieved in six steps from commercially available material. Evans' aldol reactions were utilized followed by Weinreb amide formation and Mitsunobu inversion to achieve the necessary st
- Pearson, Clay,Rinehart, Kenneth L.,Sugano, Michihiro
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p. 411 - 414
(2007/10/03)
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- Aplyronine A, a potent antitumor substance of marine origin, aplyronines B and C, and artificial analogues: Total synthesis and structure-cytotoxicity relationships
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The enantioselective total synthesis of aplyronine A (1), a potent antitumor substance of marine origin, was achieved by a convergent approach. Three segments 4, 5, and 6, corresponding to the C5-C11, C21-C27, and C28-C34 portions of aplyronine A (1), were prepared using the Evans aldol reaction and the Sharpless epoxidation as key steps. The coupling reaction of 4 with iodide 7 followed by Julia olefination with sulfone 8 gave the C5-C20 segment 9, while the Julia coupling reaction between segments 5 and 6 provided the C21-C34 segment 10. Julia olefination between segments 9 and 10 and the subsequent four-carbon homologation reaction led to seco acid 83, which was converted into aplyronine A (1) by Yamaguchi lactonization followed by the introduction of two amino acids. The use of the [(3,4-dimethoxybenzyl)oxy]methyl group as a protecting group for the hydroxyl at C29 was crucial for this synthesis. The enantioselective synthesis of two natural congeners, aplyronines B (2) and C (3), was also carried out using the intermediates for the synthesis of 1, which determined the absolute stereostructures of 2 and 3 unambiguously. To study the structure-cytotoxicity relationships of aplyronines, artificial analogues of 1 were synthesized and their cytotoxicities were evaluated: the trimethylserine moiety, two hydroxyl groups, and the side chain portion in 1 turned out to be important in the potent cytotoxicity shown by 1. Biological studies with aplyronine A (1) showed that 1 inhibited polymerization of G-actin to F-actin and depolymerized F-actin to G-actin.
- Kigoshi, Hideo,Suenaga, Kiyotake,Mutou, Tsuyoshi,Ishigaki, Takeshi,Atsumi, Toshiyuki,Ishiwata, Hiroyuki,Sakakura, Akira,Ogawa, Takeshi,Ojika, Makoto,Yamada, Kiyoyuki
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p. 5326 - 5351
(2007/10/03)
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- Total synthesis of the polyether antibiotic lonomycin A (Emericid)
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The first asymmetric synthesis of the polyether antibiotic lonomycin has been achieved. The skeleton is assembled through the synthesis and union of two subunits comprising the C1-C11 and C12-C30 portions of the
- Evans, David A.,Ratz, Andrew M.,Huff, Bret E.,Sheppard, George S.
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p. 3448 - 3467
(2007/10/02)
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- Synthetic studies on aplyronine A, a potent antitumor substance of marine origin: Stereocontrolled synthesis of the C21-C34 segment
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The C21-C34 segment 2 of aplyronine A (1), a potent antitumor substance of marine origin, was synthesized enantioselectivity in 25 steps (17% overall yield) from imide 11.
- Kigoshi, Hideo,Ojika, Makoto,Suenaga, Kiyotake,Mutou, Tsuyoshi,Hirano, Junko,Sakakura, Akira,Ogawa, Takeshi,Nisiwaki, Masanori,Yamada, Kiyoyuki
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p. 1247 - 1250
(2007/10/02)
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