Extracellular recordings were obtained from 163 visual tracking neurons in area 7a or PG (24) of alert monkeys. The firing patterns observed during movements the chair which monkey was seated with its head fixed and a target that trained to fixate continuously. Horizontal classified into three groups, A, B, C, on basis following two discharge characteristics: directional preference for response horizontal sinusoidal oscillation dark. Those did not respond oscillations dark as type A (26/53)....

The first total synthesis of (−)-gambierol (1), a marine polycyclic ether toxin, has been achieved. Key features the successful include (1) convergent union ABC and EFGH ring fragments (5 6, respectively) via our developed B-alkyl Suzuki−Miyaura cross-coupling strategy leading to octacyclic polyether core 4 (2) late-stage introduction sensitive triene side chain by use Pd(PPh3)4/CuCl/LiCl-promoted Stille coupling. fragment 5 was synthesized in linear manner (B → AB ABC), wherein A formed...

Total synthesis of structure 1 originally proposed for brevenal, a nontoxic polycyclic ether natural product isolated from the Florida red tide dinoflagellate, Karenia brevis, was accomplished. The key features involved (i) convergent assembly pentacyclic polyether skeleton based on our developed Suzuki−Miyaura coupling chemistry and (ii) stereoselective construction multi-substituted (E,E)-dienal side chain by using copper(I) thiophen-2-carboxylate (CuTC)-promoted modified Stille coupling....

Short and sweet: The highly potent antiproliferative marine macrolide (+)-neopeltolide has been synthesized based on the strategic application of olefin metathesis reactions. total synthesis proceeded in only 13 steps from commercially available starting materials, represents shortest reported to date. Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made submitted by authors. Please...

A novel strategy for the stereoselective synthesis of substituted tetrahydropyrans has been developed on basis a domino olefin cross-metathesis/intramolecular oxa-conjugate cyclization catalyzed by Hoveyda—Grubbs second-generation catalyst.

Abstract We describe herein an enantioselective total synthesis of (−)‐exiguolide, the natural enantiomer. The methylene bis(tetrahydropyran) substructure was efficiently synthesized by exploiting olefin cross‐metathesis for assembly readily available acyclic segments and intramolecular oxa‐conjugate cyclization reductive etherification formation tetrahydropyran rings. 20‐membered macrocyclic framework constructed in efficient manner means Julia–Kocienski coupling Yamaguchi...

All's well that ends well! The complete assignment of the structure largest known natural product is not a biopolymer (maitotoxin) has concluded with determination configurations stereogenic centers in its two acyclic side chains. results NMR studies were confirmed by comparison synthesized model compounds. absolute configuration was determined analysis fragment and corresponding unit GC chiral column. In contracted below, chains are attached to termini polycyclic polyether.

All's well that ends well! The complete assignment of the structure largest known natural product is not a biopolymer (maitotoxin) has concluded with determination configurations stereogenic centers in its two acyclic side chains. results NMR studies were confirmed by comparison synthesized model compounds. absolute configuration was determined analysis fragment and corresponding unit GC chiral column. In contracted below, chains are attached to termini polycyclic polyether.

The first total synthesis of gymnocin-A (1), a cytotoxic polycyclic ether isolated from notorious red tide dinoflagellate, Karenia mikimotoi, has been accomplished. relies heavily on the Suzuki−Miyaura cross-coupling-based methodology to assemble tetradecacyclic polyether skeleton. Convergent union GHI (5) and KLMN (6) rings, both which were prepared common intermediate 7, subsequent ring closure J delivered GHIJKLMN ring. crucial coupling between ABCD FGHIJKLMN fragments (3 4, respectively)...

Rapid elaboration: (+)-Neopeltolide, a novel marine metabolite with potent cytotoxicity against several cancer cell lines, was the target of an efficient total synthesis (see scheme). The construction 2,4,6-trisubstituted tetrahydropyran substructure is based on Suzuki–Miyaura coupling/ring-closing metathesis sequence. BOM=benzyloxymethyl, MPM=4-methoxyphenylmethyl, TIPS=triisopropylsilyl.

Divergent synthesis of multifunctional molecular probes based on caprolactam-derived dipeptidic γ-secretase inhibitors (GSIs), Compound E (CE) and LY411575 analogue (DBZ), was efficiently accomplished by means Cu(I)-catalyzed azide/alkyne fusion reaction. Photoaffinity labeling experiments using these derivatives coupled to photoactivatable biotin moieties provided direct evidence that the targets CE DBZ are N-terminal fragment presenilin 1 within complex. Moreover, photoprobes directly...

Journal Article Porcine Muscle Prolyl Endopeptidase and Its Endogenous Substrates Get access Akihiko Moriyama, Moriyama Department of Biochemistry, Nagoya City University Medical SchoolMizuho-ku, Nagoya, Aichi 467 Search for other works by this author on: Oxford Academic PubMed Google Scholar Makoto Nakanishi, Nakanishi Sasaki The Volume 104, Issue 1, July 1988, Pages 112–117, https://doi.org/10.1093/oxfordjournals.jbchem.a122404 Published: 01 1988 history Received: 14 March

An enantioselective total synthesis of aspergillides A and B has been accomplished based on a unified strategy, wherein hydroxy-directed, highly chemoselective olefin cross-metathesis diastereoselective intramolecular oxa-conjugate cyclization were employed to forge the 2,6-substituted tetrahydropyran substructure.

Intramolecular oxa-conjugate cyclization (IOCC) of α,β-unsaturated carbonyl compounds, triggered by deprotonation with a base, represents straightforward method for the synthesis tetrahydropyrans. However, it has been known that stereochemical outcome IOCC depends on local structure substrates and sometimes requires harsh reaction conditions and/or prolonged times selective formation 2,6-cis-substituted These shortcomings limit feasibility in context complex natural product synthesis. In...

Gambierol is a potent neurotoxin that belongs to the family of marine polycyclic ether natural products and primarily targets voltage-gated potassium channels (K(v) channels) in excitable membranes. Previous work chemistry ethers has suggested critical importance full length skeleton for biological activity. Although we have previously investigated structure-activity relationships (SARs) peripheral functionalities gambierol, it remained unclear whether whole needed its cellular In this work,...

Total synthesis of gambieric acid A, a potent antifungal polycyclic ether metabolite, has been accomplished for the first time, which firmly established complete stereostructure this natural product.

A general method for convergent assembly of polyether structure has been developed based on palladium(0)-mediated Suzuki cross-coupling reaction alkylboranes with cyclic ketene acetal phosphates. The present allowed coupling medium-sized ether rings and thus a concise synthesis the ABCD ring system ciguatoxins achieved.

A new excitatory amino acid, neodysiherbaine (2), was isolated as a minor constituent of the aqueous extract from marine sponge Dysidea herbacea. The structure deduced by spectroscopic methods and established unambiguously total synthesis. present synthesis, including key step cross-coupling 6/5-bicyclic core with an acid residue, is useful in constructing its structural analogues.

A highly convergent total synthesis of gymnocin-A, a cyctotoxic polyether marine natural product, has been achieved. The features Suzuki-Miyaura coupling the ABCD and FGHIJKLMN rings, stereoselective introduction C17 hydroxyl group, ring-closure F ring, late-stage incorporation 2-methyl-2-butenal side chain.

The polycyclic ether class of marine natural products presents formidable and challenging synthetic targets due to their structural complexity exceptionally potent biological activities. We have developed a highly convergent strategy for the assembly huge array, which features Suzuki-Miyaura cross-coupling alkylboranes, generated from exocyclic enol ethers, with cyclic ketene acetal triflates or phosphates combined reductive ring-closure. utility this was demonstrated by its application...