Results 171 to 180 of about 3,978 (197)
Some of the next articles are maybe not open access.
Synthesis of a marine polyether toxin, okadaic acid (3) — synthesis of segment c
Tetrahedron, 1987Abstract 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 . Synthesis of the segment C in the optically active natural form starting from a D-glucose derivatives is described.
Yoshiyasu Ichikawa +4 more
openaire +1 more source
Synthesis of a marine polyether toxin, okadaic acid [4]p1 -- total synthesis
Tetrahedron, 1987Abstract 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 +4 more
openaire +1 more source
Biosynthetic origin of C-37 and C-38 in the polyether toxins okadaic acid and dinophysistoxin-1
Journal of the Chemical Society Chemical Communications, 1994Stable isotope incorporation experiments have shown that carbons 37 and 38 in okadaic acid and dinophysistoxin-1 are derived from glycolate.
Judy Needham
exaly +2 more sources
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 ...
openaire +2 more sources
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 ...
openaire +2 more sources
Synthesis of a marine polyether toxin, okadaic acid [1] — strategy and synthesis of segment a
Tetrahedron, 1987Abstract 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 +3 more
openaire +1 more source
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 +5 more
openaire +4 more sources
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 +5 more
openaire +4 more sources
Food Additives and Contaminants, 1993
A brief summation of the methods for detection of each of the marine toxins is presented in this report. The toxins are brevetoxin (PbTx), palytoxin (PTX), okadaic acid (OA), paralytic shellfish toxins (PSP) and ciguatoxin (CTX). The immunological and biotechnical procedures developed for each of these toxins are reviewed.
openaire +2 more sources
A brief summation of the methods for detection of each of the marine toxins is presented in this report. The toxins are brevetoxin (PbTx), palytoxin (PTX), okadaic acid (OA), paralytic shellfish toxins (PSP) and ciguatoxin (CTX). The immunological and biotechnical procedures developed for each of these toxins are reviewed.
openaire +2 more sources
Tetrahedron: Asymmetry, 1992
Abstract Stereoselective reductions of compound 5, by means of(+)-B-chlorodiisopinocampheylboraned led to 6 with a good selectivity. Intramolecular hetero-Michael cyclization of 13 with NaH in HMPA gave 14 with an excellent selectevity.
Didier Desmaële +2 more
exaly +2 more sources
Abstract Stereoselective reductions of compound 5, by means of(+)-B-chlorodiisopinocampheylboraned led to 6 with a good selectivity. Intramolecular hetero-Michael cyclization of 13 with NaH in HMPA gave 14 with an excellent selectevity.
Didier Desmaële +2 more
exaly +2 more sources
Brevetoxin B1, a new polyether marine toxin from the New Zealand shellfish, Austrovenus stutchburyi
Tetrahedron Letters, 1995Abstract 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 +10 more
openaire +1 more source
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 +3 more
openaire +1 more source
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 +3 more
openaire +1 more source