Showing papers in "Tetrahedron Letters in 1987"

TL;DR: In this article, a trialkoxy-diphenyl-methylester and amide linkage for solid-phase peptide synthesis with Fmoc strategy is described, which can be smoothly cleaved with weak acid, resulting in fragments with intact side-chain protection.

TL;DR: In this article, the use of lithium hydroperoxide for the highly regioselective hydrolysis of a range of carboximides is described, and several cases are provided where the reagent exhibited dramatically different than the complementary reactions with hydroxide.

TL;DR: Sodium borohydride reduction of β-hydroxyketones in presence of alkoxydialkylboranes 1−7 as complexing agents, produced 1,3- syn diols in at least 98:2 ratio as discussed by the authors.

TL;DR: In this article, a novel polyether toxin, yessotoxin, was isolated from scallops implicated in diarrhetic shellfish poisoning, and its planar structure was proposed by means of modern NMR techniques.

TL;DR: In this article, thermally stable 1,2-dioxetanes bearing tert-butyldimethylsilyloxyaryl groups have been prepared and react with fluoride ion at ambient temperature in MeCN and DMSO with efficiencies up to 25%.

TL;DR: In this paper, the authors propose a rapid and efficient way to obtain esters of primary and secondary alcohols, provided there is a hydrogen atom on the carbon adjacent to the carbonyl of the acyl moiety.

TL;DR: Structure 1 is proposed to represent the product of reaction of methyl thioglycolate with the neocarzinostatin chromophore and a mechanism for the formation of 1 is presented which provides a rationale for the nucleophilic activation of neocarcinostatin.

TL;DR: The preparation of an aryl phosphate-substituted 1,2-dioxetane and the enzymatic cleavage of this chemiluminescent dioxetanes in aqueous buffer with alkaline phosphatase are described.

TL;DR: In this paper, a phenyldimethylsilyl group attached to carbon can be converted into a hydroxyl group using either bromine or mercuric ion in an acetic acid solution of peracetic acid.

TL;DR: A thermally stable 1,2-dioxetane bearing a naphthyl acetate group is enzymatically cleaved in aqueous buffer to generate chemiluminescence at ambient temperature.

TL;DR: In the presence of n -Bu4NCl, DMF and an appropriate base (Na2CO3, NaOAc or Et3N) cyclize nitrogen-containing o -iodoaryl alkenes to indoles, indolines,3 oxindoles, quinolines and isoquinolines.

TL;DR: In this article, secondary amines with hydrogen peroxide in the presence of selenium dioxide catalyst at room temperature gives nitrones, which are versatile synthetic intermediates, highly efficiently.

TL;DR: The synthesis of the new polymeric support of type 7 for the preparation of C-terminal peptide amides by the Fmoc method is described and Cleavage of the peptideAmides is performed by very mild acidolysis.

TL;DR: The lower order mixed cuprate derived from CuCN and 2-lithiothiophene (i.e., 2-ThCu(CN)Li) is found to have excellent shelf life, thereby providing an easily formed yet itself unreactive precursor to higher order mixed organocuprates as discussed by the authors.

TL;DR: A convenient method for the preparation of 65–85 g quantities of Cp2Zr(H)Cl, Schwartz's reagent has been developed and is of high purity and has several advantages over the reagent prepared by previously reported methods.

TL;DR: The cytotoxic extract of Psammaplysilla sp. collected from Tonga contains monobromo tyrosine derivatives, 3-bromo-4-hydroxyphenylacetonitrile (1), which is known and psammaplin A (2) which is the first disulfide to be isolated from a sponge.

TL;DR: Using [Cp(Me)5Rh(bipy)C1]C1 (1) as redox catalyst for the continous NADH regeneration, it was possible to perform an electrochemically driven enzymatic reduction of pyruvate to D-lactate catalyzed by D-LDH at a rate of 5 turnovers per hour as discussed by the authors.

TL;DR: In this paper, Fmoc-amino acids are added to 4-alkoxybenzyl alcohol polystyrene by 2,6-dichlorobenzoyl chloride, which is free of the two side-reactions observed with dicyclohexyl carbodiimide/4-dimethylaminopyridine, viz. racemization and dipeptide formation.

TL;DR: In this paper, Lycopadiene (2.6R,10R,14,19,23R,27R,31 -octamethyldotriaconta- 14(E), 18(E)-diene) has been isolated from the hexane extract of new strains of the green colonial alga Botryococcus braunii.

TL;DR: In this paper, the stereoselective aldol addition reactions of chiral haloacetate enolates is reported. And the conversion of these adducts to enantiomerically pure anti-β-hydroxy-α-amino acids is demonstrated.

TL;DR: Keramamine-A and -B, two β-carboline alkaloids with a 13 membered ring have been isolated from the Okinawan marine sponge Pellina sp. as mentioned in this paper.

TL;DR: The title compounds were isolated from a marine sponge collected off Okinawa and determined by X-ray and shown to be 1-β-carbolines as mentioned in this paper, the 2-ethyl-N-azacycloundec-6-ene derivative of dihydromanzamine A.

TL;DR: Aryl boronic acids have been obtained by metalation-B(OMe) 3 or metalation silylation-ipso borodesilylation sequences as discussed by the authors.

TL;DR: The chiral N-acyl oxazolidones 2, as the derived dibutyl boron enolates, have been demonstrated to undergo diastereoselective bromination and subsequent azide displacement to give the α-azido carboximides 4a (5 cases) as mentioned in this paper.

TL;DR: An optically active ferrocenylphosphine ligand containing 2-(morpholino)ethylamino or 2-(piperidino)ethylamino group on the ferrocene side chain was effective for the gold-catalyzed aldol reaction of methyl isocyanoacetate with aldehydes as discussed by the authors.

TL;DR: In this article, the synthesis of ( + )-pinitol in 35% overall yield from benzene has been achieved where the key step involved microbial oxidation of benzene to cis -1,2-dihydroxycyclohexa-3,5-diene.

TL;DR: In this paper, secondary amines react with carbon dioxide and terminal alkynes in the presence of a catalytic amount of 4-1,5-cyclooctadiene (COD), 6- 1,3,5 cyclooctatriene [Ru(COD)(COT)] and tertiary phosphine in toluene to give enol carbamates in good yields with high regio and stereoselectivity.

TL;DR: In this article, Ntert-Butoxycarbonylated 2-oxazolidinones and tetrahydro-2oxazinones are smoothly cleaved to acyclic N-Boc-amino alcohols on treatment with catalytic amounts of cesium carbonate at room temperature.

TL;DR: In this paper, it was shown that RCu add readily in a conjugate fashion to enones in the presence of TMSCl and TMEDA to give high yields of trimethylsilyl enol ethers.

TL;DR: In this article, the reductive homocoupling of aromatic and α, β-unsaturated aldehydes was found to yield symmetrical 1, 2-diols with high threo -selectivity.