Stereoselective synthesis of the C-24 and C-25 stereoisomeric pairs of 24-ethyl-26-hydroxy- and 24-ethyl-[26-2H]sterols and their Δ22-derivatives: reassignment of13C n.m.r. signals of the pro-R and the pro-S methyl groups at C-25 of 24-ethylsterols
- 1 January 1989
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 11,p. 1957-1967
- https://doi.org/10.1039/p19890001957
Abstract
Two C-24 and C-25 epimeric pairs of 24-ethyl-26-acid sterol derivatives (22)–(25) were stereoselectively synthesized via an ester-enolate Claisen rearrangement of the (22R)-(20) and (21) and (22S)-23E-ene derivatives (18) and (19). The absolute configuration at C-24 and C-25 of methyl (22E,24S,25S)-6β-methoxy-3α,5-cyclo-5α-stigmast-22-en-26-oate (22a) and (22E,24R,25R)-6β-methoxy-3α,5-cyclo-5α-stigmast-22-en-26-oic acid (24) were confirmed by X-ray crystallography. Four C-24 and C-25 epimeric pairs of 24-ethyl-[26-2H]-(34)–(37) and 24-ethyl-26-hydroxy-sterols (42)–(45) and their Δ22-derivatives (38)–(41) and (46)–(49) have been synthesized in order to study the stereochemistry in the biosynthesis of (24R)- and (24S)-24-ethylsterol side-chains. The data showed that C-26 and C-27 arise biosynthetically from C-6 and C-2 of MVA, respectively.This publication has 10 references indexed in Scilit:
- Acyclic stereoselection. Part 42. 1,4- and 1,5-Stereoselection by sequential aldol addition to a .alpha.,.beta.-unsaturated aldehydes followed by Claisen rearrangement. Application to total synthesis of the vitamin E side chain and the archaebacterial C40 diolThe Journal of Organic Chemistry, 1988
- Biosynthesis of sitosterol, cycloartenol, and 24-methylenecycloartanol in tissue cultures of higher plants and of ergosterol in yeast from [1,2-13C2]- and [2-13C2H3]-acetate and [5-13C2H2]MVAJournal of the Chemical Society, Perkin Transactions 1, 1987
- Synthesis of (25R)-[26-2H1]cholesterol and 1H n.m.r. and h.p.l.c. resolution of (25R)- and (25S)-26-hydroxycholesterolJournal of the Chemical Society, Perkin Transactions 1, 1987
- Synthesis of (25S)-[26-2H1]cholesterol and 1H N.m.r. signal assignments of the pro-R and pro-S methyl groups at C-25Journal of the Chemical Society, Perkin Transactions 1, 1986
- The C-25 chirality of 26-hydroxycholesterolThe Journal of Organic Chemistry, 1981
- Stereochemical fate of the isopropylidene methyl groups of lanosterol during the biosynthesis of isofucosterol in Pinus pineaJournal of the Chemical Society, Perkin Transactions 1, 1981
- Stereospecific synthesis of the side chain of the steroidal plant sex hormone oogoniolThe Journal of Organic Chemistry, 1979
- Identification of C-24 alkyl epimers of marine sterols by 13C nuclear magnetic resonance spectroscopyCanadian Journal of Chemistry, 1978
- Biosynthesis of β-sitosterol from [4-13C]mevalonic acid and sodium [1,2-13C]acetate in tissue cultures of Isodon japonicus haraJournal of the Chemical Society, Chemical Communications, 1978
- Carbon-13 NMR studies on cholesterol biosynthesized from [13C]mevalonatesJournal of the American Chemical Society, 1977