scispace - formally typeset
Search or ask a question

Showing papers in "Tetrahedron Letters in 1989"


Journal ArticleDOI
TL;DR: A general synthetic procedure for new derivatives of different N-hydroxy compounds has been developed and these either act as excellent activating reagents causing low racemization during condensation of peptide segments or are useful tools for the formation of active esters suitable for couplings in mixed aqueous / organic media, respectively.

950 citations


Journal ArticleDOI
TL;DR: In this paper, the 2-chlorotrityl resin 3c fulfills all requirements needed to obtain the desired fragments in high yield and purity, using Fmoc-amino acids protected at their side chains with groups of the t-butyl type.

326 citations


Journal ArticleDOI
TL;DR: In this paper, the Wittig reaction of iodomethylenetriphenylphosphorane with aldehydes was used to synthesize (Z)-1-iodo-1-alkenes.

318 citations


Journal ArticleDOI
TL;DR: The reaction of three moles of vinylmagnesium bromide with one mole of nitroarene leads to the formation of indoles after aqueous work up of the mixture as mentioned in this paper.

249 citations


Journal ArticleDOI
TL;DR: In this article, a method for the selective diametrical functionalization of calix[4]arenes at the upper rim by transfer of functionality and selective substitutions at the para positions of the phenol rings is described.

245 citations


Journal ArticleDOI
TL;DR: In this paper, Thioacetals and thioketals can be cleaved to carbonyl compounds in high yields by treatment with bis (trifluoroacetoxy)iodobenzene.

242 citations


Journal ArticleDOI
TL;DR: Triethylsilane was used as a scavenging agent in peptide synthesis for the removal of protecting groups with TFA as discussed by the authors, and the efficiency of scavenging ability was compared with anisole and ethanedithiol in a kinetic experiment.

218 citations


Journal ArticleDOI
TL;DR: In this paper, N-Methyl p-toluenesulfonamide and N-BOC p-Toluene sulfonamide can be directly coupled with primary and secondary alcohols under Mitsunobu conditions to afford various sulfoneamide-protected amines.

194 citations


Journal ArticleDOI
TL;DR: The addition of diethylzinc-orthotitanate complex to benzaldehyde catalyzed by 0.0001∼0.04 equiv of chiral sulfonamide-titanate in toluene at 0∼ −30° gives optically active 1-phenylpropanol in both high ee and chemical yields as discussed by the authors.

184 citations


Journal ArticleDOI
TL;DR: Acyclic conjugated allenylphosphine oxide 4b prepared by three step operations was stable at ambient temperature and underwent Bergman type cyclization to form biradical 5b at 37 °C as discussed by the authors.

181 citations


Journal ArticleDOI
TL;DR: Palladium(0)-catalysed coupling of aryl and vinyl triflates or halides with the easily available 2-ethynylaniline, followed by a palladium(II)catalysed cyclization step, provides an efficient and very versatile procedure for the synthesis of functionalyzed 2-substituted indoles.

Journal ArticleDOI
TL;DR: In this paper, an efficient synthetic route to either R - or S -fluoxetine is described which depends on the use of a chiral, enzyme-like catalyst (chemzyme) to establish the stereocenter and which makes these important therapeutic agents readily available in enantiomerically pure form.

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the relative lability of benzhydrylamine and benzylamine linkage agents for the solid phase peptide synthesis of C-terminal amides and compared them with the N α -9-fluorenylmethyloxycarbonyl protecting group strategy.

Journal ArticleDOI
TL;DR: In this paper, acid-sensitive functionalities such as acetonide and silyloxy groups are efficiently converted to the corresponding cyclic sulfates via formation of the cyclic sulphites in the presence of a base and oxidation of the isolated sulfites using catalytic RuO4.

Journal ArticleDOI
TL;DR: The structure of N-methyl benzanilide was elucidated by X-ray analysis and examination of 1H- and 13C-nmr spectra as mentioned in this paper, and the stereochemistry of the amide bond was proved to be cis in the crystal and in solution.

Journal ArticleDOI
TL;DR: In this article, the absolute configurations of marine diterpenes, 7 and 8, were elucidated by means of Mosher's method using 1H NMR spectroscopy at 500 MHz.

Journal ArticleDOI
TL;DR: In this paper, the acylsultams were treated with nBuLi or NHMDS and primary alkyl halides, followed by crystallization, giving pure C(α)-alkylation products and enantiomerically pure alcohols.

Journal ArticleDOI
TL;DR: In this article, the reaction of Et 2 Zn-Ti(O- i -Pr) 4 -disulfonamide with various aldehydes was examined and it was shown that high enantioselectivity (> 90% e.g.

Journal ArticleDOI
TL;DR: In this article, the use of ( c -C 6 H 11 ) 2 BCl in the anti-selective aldol reaction of the α-chiral ethylketone 2 leads to high stereoselectivity (>94%) for the 1,2- anti -2,4- anti isomer.

Journal ArticleDOI
TL;DR: In this paper, a novel analogue of 3′-deoxythymidine, in which the 3′ carbon is replaced by oxygen, was synthesized in 5 steps from benzyloxyacetaldehyde dimethyl acetal and (±)-methyl glycerate.

Journal ArticleDOI
TL;DR: In this paper, an efficient synthesis of (S) -(−)-2-(di-β-naphthylhydroxymethyl)pyrrolidine (1 ) makes available the oxazaborolidine derivatives 2 and 3 which are excellent catalysts for borane reduction of achiral ketones to chiral secondary alcohols, e.g.

Journal ArticleDOI
TL;DR: Silane3 is an effective mediator in organic synthesis via radicals as discussed by the authors, and reactions with this silane give smaller amounts of unwanted reduction products than reactions with toxic stannanes.

Journal ArticleDOI
TL;DR: In this paper, the esterification of partially protected peptide fragments through the C-terminal or a free side chain carboxy group with hydroxy groups containing resins and the 2-chlorotritylchloride resin 8 is described.

Journal ArticleDOI
TL;DR: In this paper, the perfluoroalkyl iodides were used for the treatment of terminal or internal acetylenes bearing a variety of substituents, in the presence of a catalytic amount of triethylborane.

Journal ArticleDOI
TL;DR: The Zr-promoted bicyclization of 1,6-and 1,7-dienes can stereoselectively produce trans-zirconabicyclo[3.3.0] octanes and cis-Zircon-conabicycleclo [4.3] nonanes, respectively; these compounds can be readily converted into protonolysis, halogenolysis and carbonylation products as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, the use of Cp2HfCl2-AgClO4 in 1:2-ratio rather than 1:1-ration provides much higher reactivity for the activation of glycosyl fluoride.

Journal ArticleDOI
TL;DR: The t -Boc group activated the α-lithiation of piperidinyl and related carbamates to give lithium reagents which add to electrophiles to provide α-elaborated β-caramates as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, simple exposure of n-Bu3SnH to Bu2Cu(CN)Li2 in THF at low temperatures leads directly to the presumed mixed higher order trialkyltin cuprate, the reactions of which selectively transfer the trialkylstannyl group to a variety of substrates.

Journal ArticleDOI
TL;DR: In this paper, three cytotoxic macrolides, mycalolides A and C have been isolated from a sponge Mycale sp., and their structures elucidated to be hybrids of ulapualides and halichondramide mainly by analyses of 2D NMR spectra as well as by comparison of spectral data.

Journal ArticleDOI
TL;DR: In this paper, a one-pot transformation of a homopropargyl alcohol to regio- and stereo-defined trisubstituted homoallyl alcohols has been achieved by a sequence of intramolecular hydrosilation and the palladium-catalyzed coupling reaction.