Neighboring group participation in epoxide ring cleavage in reactions of some 16α,17α-oxidosteroids with lithium hydroperoxide

Morzycki, Jacek W.; Gryszkiewicz, Agnieszka; Jastrzębska, Izabella

doi:10.1016/s0040-4020(01)00051-5

Cited by 27 publications

(21 citation statements)

References 17 publications

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“…Compound 6 was obtained through the cascade intramolecular redox/ketalization of 7, and ring E was prepared from 8, after epoxidation or dihydroxylation, through a cascade methanolysis/intramolecular epoxide opening or S N 2 process. Compound 8 was prepared from tigogenin acetate (9): ring E was opened via a cascade iodo-lactonization process and the C16-C17 double bond was obtained via the elimination of the resulting C16a-I.…”

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confidence: 99%

Synthesis of the aglycon of aspafiliosides E and F based on cascade reactions

Shi

Tian

2016

Chem. Commun.

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A synthesis of C17α-OH-tigogenin, the aglycon of aspafiliosides E and F, is described. The main features of the synthesis are three cascade processes, which involve the iodo-lactonization of furostan-26-acid to open ring E, a cascade hydrolysis/intramolecular SN2 process to close ring E, and a cascade intramolecular redox-ketalization process to close ring F. This synthesis would enrich the strategies used for the manipulation of spiroketals in steroidal sapogenins and other substrates.

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confidence: 99%

Synthesis of the aglycon of aspafiliosides E and F based on cascade reactions

Shi

Tian

2016

Chem. Commun.

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“…The formation of this compound with a heteroaromatic ring E under acidic conditions from OSW-1 aglycone via a Ferrier type of rearrangement was reported several times in the literature. 12,34,35 The anticancer activity of the new OSW-1 analogues was evaluated in vitro using eight cancer cell lines of different histopathological origins and normal mouse fibroblast NIH 3T3 cells. The results are summarized in Table 2.…”

Section: Resultsmentioning

confidence: 99%

New Analogues of the Potent Cytotoxic Saponin OSW-1

et al. 2007

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Saponin OSW-1 (5e-G2; 3 beta,16 beta,17 alpha-trihydroxycholest-5-en-22-one 16-O-{O-[2-O-(4-methoxybenzoyl)-beta-D-xylopyranosyl]-(1-->3)-2-O-acetyl-alpha-arabinopyranoside}) analogues: with modified side chain (5a/d-G2), 22-deoxo-23,24,25,26,27-pentanor- (14), 22-deoxo-23-oxa- (17), glycosylated with various monosaccharides (5e-G4/G6/G8), and OSW-1 structural isomer (10) were obtained. The analogues were synthesized using a previously published method for the synthesis of OSW-1. The structures of analogues were fully confirmed by spectroscopic methods, and the S-chirality at C-22 of the structural isomer was established by conformational analysis combined with the NMR spectrometry. The cytotoxicity of the analogues toward several types of malignant tumor cells was examined and compared with that of OSW-1. The results suggest that modification of the steroidal aglycone may lead to compounds with high cytotoxicity.

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“…The D-ring double bond was subjected to epoxidation with MCPBA. The obtained 16a,17a-epoxide 31 underwent ring opening with LiOH/H 2 O 2 via an intramolecular mechanism (Morzycki et al, 2001b). The primary reaction product, 16b,17a-dihydroxy-22-carboxylic acid, spontaneously cyclized to the 17a-hydroxy lactone 32, the key-precursor in further synthesis of saponin OSW-1.…”

Section: Synthesis Of Saponin Osw-1 and Its Analoguesmentioning

confidence: 99%