Results 161 to 170 of about 91,656 (195)

Tetrahydropyran Formation by Rearrangement of an Epoxy Ester:  A Model for the Biosynthesis of Marine Polyether Toxins

The Journal of Organic Chemistry, 2004
Acid-catalyzed rearrangement of the (S)-epoxide derived from 2alpha-allyl cholestanyl acetate resulted in a 1:1 mixture of a steroidal tetrahydrofuran and a steroidal tetrahydropyran. Formation of a six-membered ring supports the hypothesis that epoxy ester-orthester-cyclic ether rearrangement may be involved in the biosynthesis of ladder-type marine ...
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Synthesis of a marine polyether toxin, okadaic acid (2) — synthesis of segment b

Tetrahedron, 1987
Abstract The central synthetic segment B for okadaic acid comprises the carbons from 15 through 27 including 6 asymmetric carbons. Its synthesis started from a D-Glucose derivative, whose carbon was extended twice for the six and five membered etherial ring formation. The original conformation of the sugar was inverted when the spiro-ether was formed
Yoshiyasu Ichikawa, Minoru Isobe, Toshio Goto   +2 more
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Synthesis of a marine polyether toxin, okadaic acid [4]p1 -- total synthesis

Tetrahedron, 1987
Abstract Three segments A, B and C for okadaic acid synthesis were coupled with each other in the order of A+(B+C), the key steps of the twice couplings being between sulfone carbanions and aldehydes. After the B+C coupling, the asymmetric center C-27 was generated by a hydride reduction of the corresponding ketone 16 under electronic control.
Minoru Isobe, Yoshiyasu Ichikawa, Dong-Lu Bai, Hisanori Masaki, Toshio Goto   +4 more
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Synthesis of a marine polyether toxin, okadaic acid [1] — strategy and synthesis of segment a

Tetrahedron, 1987
Abstract The title compound was divided into three retrosynthetic segments A, B and C, by disconnecting two C-C bonds at C- 14 15 and C- 27 28 . Segment A for okadaic acid synthesis comprises the carbon skeleton from C-1 through C-14, which was further disconnected at the bonds between C-8 and C-9 into two fragments A1 and A2.
Yoshiyasu Ichikawa, Minoru Isobe, Dong-Lu Bai, Toshio Goto   +3 more
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Rapid determination of polyether marine toxins using liquid chromatography–multiple tandem mass spectrometry

Journal of Chromatography A, 2004
The diarrhetic shellfish poisoning (DSP) toxins, okadaic acid (OA), dinophysistoxins (DTX); pectenotoxin-2 (PTX2) and pectenotoxin-2 seco acids, were determined in marine phytoplankton, Dinophysis acuta, and mussels (Mytilus edulis) collected along the southwest coast of Ireland.
Puente, Patricia Fernández, Sáez, María José Fidalgo, Hamilton, Brett, Lehane, Mary, Ramstad, Hanne, Furey, Ambrose, James, Kevin J.   +6 more
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Elucidation of the mass fragmentation pathways of the polyether marine toxins, dinophysistoxins, and identification of isomer discrimination processes

Rapid Communications in Mass Spectrometry, 2012
RATIONALE Most of the liquid chromatography/mass spectrometry (LC/MS) methods that have been developed for the analysis of Diarrhetic Shellfish Poisoning (DSP) toxins in shellfish and algae samples have been unable to differentiate the isomers okadaic acid (OA) and dinophysistoxin‐2 (DTX2), unless separated by ...
Carey, Bébhine, Sáez, Maria José Fidalgo, Hamilton, Brett, O'Halloran, John, Van Pelt, Frank N. A. M., James, Kevin J.   +5 more
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Studies of polyether toxins in the marine phytoplankton, Dinophysis acuta, in Ireland using multiple tandem mass spectrometry

Toxicon, 2004
Diarretic shellfish poisoning (DSP) is a toxic syndrome associated with the consumption of bivalve molluscs. The DSP toxins are polyether compounds, which include okadaic acid (OA), dinophysistoxins (DTXs), pectenotoxins (PTXs) and pectenotoxin seco acids (PTX2SAs).
Puente, Patricia Fernández, Sáez, María José Fidalgo, Hamilton, Brett, Furey, Ambrose, James, Kevin J.   +4 more
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Model studies directed towards microalga polyether toxins. A stereoselective entry into C8 oxepane subunits

Tetrahedron Letters, 1991
Abstract A new synthetic strategy for the regio and stereospecific synthesis of meso β-alkoxy-substituted oxepanes involving iodine promoted transannular ring expansion of 9-oxobicyclo (6.1.0) non-4-en-2-one was studied. Stereocontrolled 1,4-dioxygenation of oxepadienes using single oxygen addition occurs trans to the existing substituents and ...
Eleuterio Alvarez, M.Teresa Díaz, Ricardo Pérez, Julio D. Martín   +3 more
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Biosynthetic origin of C-37 and C-38 in the polyether toxins okadaic acid and dinophysistoxin-1

Journal of the Chemical Society, Chemical Communications, 1994
Stable isotope incorporation experiments have shown that carbons 37 and 38 in okadaic acid and dinophysistoxin-1 are derived from glycolate.
Judy Needham, Jack L. McLachlan, John A. Walter, Jeffrey L. C. Wright   +3 more
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Brevetoxin B1, a new polyether marine toxin from the New Zealand shellfish, Austrovenus stutchburyi

Tetrahedron Letters, 1995
Abstract A new polyether marine toxin, brevetoxin B 1 , was isolated from a methanol extract of the New Zealand shellfish, Austrovenus stutchburyi , by chromatography on columns of SiO 2 , ODS, and LH-20, followed by reverse-phase HPLC and its structure was elucidated by comparison of its spectral data with those of brevetoxins B and use of NMR ...
Hitoshi Ishida, Akira Nozawa, Kazuhiro Totoribe, Norio Muramatsu, Haruo Nukaya, Kuniro Tsuji, Kentaro Yamaguchi, Takeshi Yasumoto, Henry Kaspar, Natasha Berkett, Takuo Kosuge   +10 more
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