Showing papers in "Tetrahedron Letters in 1983"

TL;DR: In this article, new phosphonoester reagents and reaction conditions are described which yield Z-alpha, beta-unsaturated esters stereoselectively and in high yield from aliphatic and aromatic aldehydes.

TL;DR: In this article, various deoxynucleoside N,N-dialkylaminomethoxyphosphines were examined for stability and reactivity in deoxyoligonucleotide synthesis.

TL;DR: In this article, a new template-based strategy was developed for synthesizing catenanes, based on a generalized template effect, as shown in Figure 1, and the first example of a novel class of molecules, the metallo-catenanes, has been obtained in good yield: it contains copper and macrocyclic phenanthroline derivatives.

TL;DR: Alkynyl boranes, generated in situ from lithium acetylides and boron trifluoride etherate, were found to react with oxiranes under mild reaction conditions to afford β-hydroxyacetylenes in high yields.

TL;DR: In this article, β-Cyanoethyl monochlorophosphoamidites of the secondary amines N, N-dmethylamine, N,N-diisopropylamine and morpholine have been prepared which showed quantitative phosphitylation of the protected deoxynucleosides.

TL;DR: C-acylation of lithium enolates by methyl cyanoformate provides high yields of β-keto esters under mild conditions and with 100% regioselectivity as mentioned in this paper.

TL;DR: Alkenyl iodide (or bromide) is readily reduced with CrCl2 is N,N-dimethylformamide at 25°C to gice the corresponding organochromium species which adds selectively to an aldehyde moiety without affecting the coexisting ketone or cyano group of the substrate.

TL;DR: Enol triflates can be prepared in high yield from regiospecific generated enolates by trapping with N-phenyltrifluoromethanesulfonimide.

TL;DR: A general chemoselective method for the reduction of azides into primary amines was described in this article, where the reduction was carried out by using a general method for azides.

TL;DR: The reaction of organozincs with acyl chlorides catalyzed by palladium-phosphine complexes, e.g., Pd(PPh 3 ) 4, provides a highly general and convenient route to ketones as mentioned in this paper.

TL;DR: Samarium diiodide is an excellent reagent for aldehyde or ketone coupling as mentioned in this paper, and reactions are very fast with a complete selectivity versus substituents such as cyano, carboxyl or nitro groups.

TL;DR: In this article, a new method for five-membered ring annulation is described which involves free radical generation from ketones by zinc-trimethylchlorosilane followed by internal addition to a π-bond.

TL;DR: In this article, the intermolecular Diels-Alder reactions employing dienophiles 1 and 5 with diene 2 have been examined in water and significantly enhanced rates, as well as the improved selectivity observed in water stand in sharp contrast to the results observed in hydrocarbon solvents.

TL;DR: The structure of Pyoverdine Pa, the siderophore of Pseudomonas aeruginosa, was elucidated by degradation, by FAB mass spectrometry and by NMR; it consists of a linear octapeptide bound to a 2,3-diamino-6,7-dihydroxyquinoline derived chromophore as discussed by the authors.

TL;DR: In the presence of a hydroxyl group juxtaposed for participation, NaBH(OAC)3 reduced even ketones in a stereo and regiospecific manner and in excellent yields as discussed by the authors.

TL;DR: Carboxylic acid esters derived from N-hydroxy-pyridine-2-thione react with carbon tetrachloride, bromotrichloromethane or iodoform in a radical chain reaction to give the corresponding noralkyl chlorides or iodides in high yield.

TL;DR: The structure of genotoxic metabolite, streptindole, isolated from intestinal bacteria (Streptococcus faecium IB 37) has been established as 2,2-di(3-indolyl) ethyl acetate by spectroscopic and synthetic methods as discussed by the authors.

TL;DR: In this article, the structures of fosfazinomycins A and B, phosphorus containing antibiotics, have been established by spectral evidence and degradation studies, and they have been shown to have similar properties to those of FOSFAS.

TL;DR: Acylation of readily available 3-methyl-3-hydroxymethyl oxetane (2) leads to the corresponding Oxetane esters (3 ) which rearrange smoothly in the presence of boron trifluoride etherate in methylene chloride at −15° to form ortho esters of the 2, 6, 7-trioxabicyclo[2.2] octane series (4 ).

TL;DR: In this article, it was shown that the oxidation of ketone hydrazones by iodine in the presence of a base to furnish vinyl iodides has been improved by three factors: absence of water, the use of strong guanidine bases and inverse addition.

TL;DR: In this article, the structure-stereoselectivity relationship between α-hydroxy ketones and zinc horohydride has been investigated and α-butyldiphenylsilyoxy derivatives with sodium bis(2methoxyethoxy)aluminum hydride gave the isomeric threoglycols.

TL;DR: The structure of the lipid A component of E. coli lippopolysaccharide was determined by means of chemical and 2D-NMR methods unequivocally to be a glucosamine β(1′-6)-disaccharide 1,4′-diphosphate acylated at the two hydroxyl (positions C-3 and −3′) and the two amino groups.

TL;DR: In this paper, structures for solanapyrones A, B and C, phytotoxins from the fungus Alternaria solani, parasite of potato, were proposed on the basis of spectroscopic data and chemical reaction.

TL;DR: In this paper, the X-B moiety was added to CC bonds in a cis fashion to accelerate the bromoboration reaction at terminal CC bonds but not at internal C�C, terminal and internal C�C bonds.

TL;DR: In this article, allyl enol carbonates, prepared from ketones or aldehydes by trapping their enolates with allyl chloroformate, to give α-allyl ketones and aldehides regioselectivity is catalyzed by palladium-phosphine complexes under mild conditions.

TL;DR: In this article, Nitrobenzaldehyde reacts smoothly with dialkylphosphonates in the presence of catalytic quantities of cinchona alkaloids (e.g. quinine) to produce the α-hydroxy phosphate esters in excellent chemical yields, with excellent enantiomeric enrichment.

TL;DR: In this paper, a general stereo-directed synthesis of komethylene and hydroxylene dipeptide isosteres was reported. But the synthesis was performed using a pepstatin with statine replaced by Leu-Ala.

TL;DR: In this paper, a practical, stereocontrolled synthesis of leukotriene B5 is described, which makes this substance readily available for the first time and can be used for medical applications.