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Showing papers in "Journal of Organic Chemistry in 1990"


Journal ArticleDOI
TL;DR: In this paper, an improved approach to the synthesis of di-disubstituted phthalocyanines from two different phthalyl precursors is described, which combines substituted 1,3 diiminoisoindoles and 6/7-nitro-1,3,3-trichloroisoindolenine to synthesize phTHC.
Abstract: An improved approach to the synthesis of di-disubstituted phthalocyanines from two different phthalyl precursors is described. The method combines substituted 1,3 diiminoisoindoles and 6/7-nitro-1,3,3-trichloroisoindolenine to synthesize phthalocyanine. The method can be applied to the synthesis of hydrogen and metallo phtahlocyanine. The yields are variable, ranging from 17% to 72% depending on the substituents.

513 citations


Journal ArticleDOI
TL;DR: Ecteinascidins 729, 743, 745, 759A,759B, and 770, tris(tetrahydroisoquinolines) with potent in vivo antitumor activity, have been isolated from the colonial tunicate EctEinascidia turbinata, and their structures have been assigned.
Abstract: Ecteinascidins 729, 743, 745, 759A, 759B, and 770, tris(tetrahydroisoquinolines) with potent in vivo antitumor activity, have been isolated from the colonial tunicate Ecteinascidia turbinata, and their structures have been assigned

449 citations


Journal ArticleDOI
TL;DR: In the presence of catalytic amounts of dichlorobis (triphenylphosphine) palladium or of the π-allylmolybdenum complex 3, tributyltin hybride adds instantaneously at room temperature to various alkynes to give the corresponding vinylstannanes in good to excellent yields as mentioned in this paper.
Abstract: In the presence of catalytic amounts of dichlorobis (triphenylphosphine) palladium or of the π-allylmolybdenum complex 3, tributyltin hybride adds instantaneously at room temperature to various alkynes to give the corresponding vinylstannanes in good to excellent yields. The reaction is totally stereoselective (cis addition). With monoalkylacetylenes RC≡CH, good regioselectivity for the formation of 1-(tributylstannyl) alkenes (vs 2-tributylstannyl) alkenes) is attained only if the R substituent is sufficiently bulky

382 citations


Journal ArticleDOI
TL;DR: The pure para isomer of title compound (I) was prepared by each of two efficient five-step routes, in overall yields from 52% to 74%, to provide a general starting point for stepwise assembly of peptide chains according to a wide range of chemistries.
Abstract: The pure para isomer of title compound (I) was prepared by each of two efficient five-step routes, in overall yields from 52% to 74%. The handle I was coupled into a variety of amino group-containing supports to provide a general starting point for stepwise assembly of peptide chains according to a wide range of chemistries. In particular, protocols based on the base-labile Nα-9-fluorenylmethyloxycarbonyl (Fmoc) group worked well with PAL handle I. A side reaction involving alkylation at tryptophan was elucidated, and conditions were developed to minimize its occurrence. The methodology was demonstrated by syntheses of over a hundred peptides, among which acyl carrier protein (65-74) amide (natural and retro sequences), luteinizing hormone-releasing hormone, adipokinetic hormone, PHI porcine fragment (18-27), and human gastrin-I are highlighted in this report

349 citations


Journal ArticleDOI
TL;DR: A new polyhydroxylated lactone, discodermolide (1), was isolated from a Caribbean marine sponge, Discodermia dissoluta, and its structure was elucidated through a combination of spectroscopic techniques, in particular NMR spectroscopy, and verified by X-ray crystallographic analysis.
Abstract: A new polyhydroxylated lactone, discodermolide (1), was isolated from a Caribbean marine sponge, Discodermia dissoluta, and its structure was elucidated through a combination of spectroscopic techniques, in particular NMR spectroscopy, and verified by X-ray crystallographic analysis. The carbon skeleton displayed by discodermolide is new; discodermolide is immunosuppressive and cytotoxic

349 citations


Journal ArticleDOI
TL;DR: Several polysulfides were tested as potential sulfur-transfer reagents during the automated synthesis of oligodeoxyribonucleoside phosphorothioates via the deoxyriboenucleosides phosphoramidite approach as discussed by the authors, and thiosulfonate 3H-1,2-benzodithiol-3-one 1,1-dioxide (12) was particularly efficient as a sulfurizing reagent
Abstract: Several polysulfides were tested as potential sulfur-transfer reagents during the automated synthesis of oligodeoxyribonucleoside phosphorothioates via the «deoxyribonucleoside phosphoramidite» approach. The thiosulfonate 3H-1,2-benzodithiol-3-one 1,1-dioxide (12) was particularly efficient as a sulfurizing reagent

295 citations


Journal ArticleDOI
TL;DR: In this paper, a chiral vaulted binaphthyl porphyrin (1) has been prepared from 5α,10β,15α,20β-tetrakis(o-aminophenyl)porphyrin and (R)-(+)-2,2'-dimethoxy-1,1'-bi-6-naphthoyl chloride in 79% yield.
Abstract: A chiral, vaulted binaphthyl porphyrin (1) has been prepared from 5α,10β,15α,20β-tetrakis(o-aminophenyl)porphyrin and (R)-(+)-2,2'-dimethoxy-1,1'-bi-6-naphthoyl chloride in 79% yield. Asymmetric oxygenations of alkanes, alkenes, and alkyl sulfides were catalyzed with the chloroiron(III) and chloromanganese(III) complexes of 1 with good yields and high stereoselectivities. The first catalytic asymmetric hydroxylations are reported for 1-Fe III Cl with enantiomeric excesses in the range of 40-72%. The corresponding manganese catalyst, 1-Mn III Cl, gave much lower enantiomeric excesses. For catalytic asymmetric epoxidations, enantiomeric excesses were in the range of 20-72%. Prochiral alkyl sulfides gave sulfoxides with 14-48% ee with 1-Fe III Cl

293 citations


Journal ArticleDOI
TL;DR: Synthese et photolyse d'azido-4 perfluoro- et -nitro-2 trifluoro -3,5,6 benzoates de methyle
Abstract: Synthese et photolyse d'azido-4 perfluoro- et -nitro-2 trifluoro-3,5,6 benzoates de methyle

291 citations


Journal ArticleDOI
TL;DR: In this paper, either cuprate or Friedel-Crafts couplings to chiral bromoglycinates were employed to unmask the oxazinone chiral auxiliary providing the free α-amino acids.
Abstract: The methodology deployed involves either cuprate or Friedel-Crafts couplings to chiral bromoglycinates. The % ee's range from 82 to 94%. Both an oxidative and reductive protocol are employed to unmask the oxazinone chiral auxiliary providing the free α-amino acids

275 citations



Journal ArticleDOI
TL;DR: The sodium tungstate catalyzed oxidation of secondary amines with hydrogen peroxide gives the corresponding nitrones.
Abstract: The sodium tungstate catalyzed oxidation of secondary amines with hydrogen peroxide gives the corresponding nitrones. Acyclic and cyclic nitrones can be obtained from secondary amines in a single step in good to excellent yields. Introduction of a substituent at the α-position of secondary amines can be performed upon oxidation of secondary amines and subsequent treatment with various nucleophiles

Journal ArticleDOI
TL;DR: Etude de la reduction totalement reversible du dication methylviologene MV 2+ vers son cation radicalaire MV 0+ and sa forme neutre MV 0, par mesures voltametriques cycliques en milieu non aqueux.
Abstract: Etude de la reduction totalement reversible du dication methylviologene MV 2+ vers son cation radicalaire MV 0+ vers son cation radicalaire MV 0+ et sa forme neutre MV 0 , par mesures voltametriques cycliques en milieu non aqueux Utilisation de solvants aprotiques conduisant aux formes cristallisees isolees de MV 0+ et MV 0 et caracterisation des structures par cristallographie X

Journal ArticleDOI
TL;DR: A bioassay guided approach was used to isolate two antitumor tetrahydroisoquinoline alkaloids, 3 and 4, from the marine ascidian Ecteinascidia turbinata.
Abstract: A bioassay guided approach was used to isolate two antitumor tetrahydroisoquinoline alkaloids, 3 and 4, from the marine ascidian Ecteinascidia turbinata. The structures of 3 and 4 were determined through spectroscopic methods

Journal ArticleDOI
TL;DR: The Ntert-butyldimethylsilyloxycarbonyl group (sily- carbamate) was synthesized from commonly used amino protecting groups such as N-tertbutoxy carbonyl (Boc) and N-benzyloxycarbononyl(Z) by treatment with tert-butiesilyl trifluoromethanesulfonate/2,6-lutidine and tert-methylsilane/Pd(OAc) 2, respectively.
Abstract: The N-tert-butyldimethylsilyloxycarbonyl group (silyl carbamate) was synthesized from commonly used amino protecting groups such as N-tert-butoxycarbonyl (Boc) and N-benzyloxycarbonyl (Z) by treatment with tert-butyldimethylsilyl trifluoromethanesulfonate/2,6-lutidine and tert-butyldimethylsilane/Pd(OAc) 2 , respectively. This novel species, upon activation with fluoride ion, reacts with a variety of electrophiles to give N-ester type compounds in high yield. For example, the conversion of N-t-Boc compounds into their corresponding N-Z compounds via a silyl carbamate was accomplished under these mild reaction conditions

Journal ArticleDOI
TL;DR: In this paper, a general rationalization for armed/disarmed effects, first recognized in n-pentenyl glycosides but recently extended to a variety of other glycosyl donors, is postulated.
Abstract: A general rationalization for armed/disarmed effects, first recognized in n-pentenyl glycosides but recently extended to a variety of other glycosyl donors, is postulated. Reaction of a glycosyl donor with an appropriate electrophile gives a positively charged intermediate which is less favorable when there is an adjacent electron-withdrawing group (for example OCOR, as in a disarmed donor) than when there is an adjacent alkoxy group (as in the armed counterpart). The latter therefore reacts faster and if, in the reaction medium, there is a disarmed species carrying a free hydroxyl group, a pathway based on Le Chatelier's principle can be envisaged that leads to products of cross-coupling with (virtually) none of the self-coupled analogue. In n-pentenyl glycosides activation of the anomeric center involves two preequilibrium steps, the second of which can be sidetracked to afford a vicinal dibromo derivative

Journal ArticleDOI
TL;DR: In this article, a most useful strategy has been devised for the synthesis of 3-substituted pyrroles on the basis of the kinetic electrophilic substitution of 1-(triisopropylsilyl) pyrrole (1) at the β position and subsequent fluoride ion induced desilylation.
Abstract: A most useful strategy has been devised for the synthesis of 3-substituted pyrroles on the basis of the kinetic electrophilic substitution of 1-(triisopropylsilyl) pyrrole (1) at the β position and subsequent fluoride ion induced desilylation. This now becomes the preferred route to 3-monosubstituted pyrroles



Journal ArticleDOI
TL;DR: In this paper, the methode presentee se fait au depart de phenyl-3 dihydroxy-2,3 propionate de methyle via epoxydation, et d'azoture de sodium.
Abstract: La methode presentee se fait au depart de phenyl-3 dihydroxy-2,3 propionate de methyle, via une epoxydation, et d'azoture de sodium; des N-t-butoxycarbonyl- et N-benzoyl phenylisoleucinates de methyle sont obtenus

Journal ArticleDOI
TL;DR: In this paper, it was shown that titanium(IV) isopropoxide is a mild and effective Lewis acid catalyst for the reductive alkylation of amines with ketones and aldehydes in the presence of acid-sensitive functional groups.
Abstract: We now report that titanium(IV) isopropoxide is a mild and effective Lewis acid catalyst for the reductive alkylation of amines with ketones and aldehydes in the presence of acid-sensitive functional groups


Journal ArticleDOI
TL;DR: In this paper, an efficient catalytic procedure for the preparation of 2-deoxyglucosides from glucals without allylic or Ferrier rearrangement using triphenylphosphine hydrobromide and a wide variety of hydroxylic nucleophiles is described.
Abstract: An efficient catalytic procedure for the preparation of 2-deoxyglucosides from glucals without allylic or Ferrier rearrangement using triphenylphosphine hydrobromide and a wide variety of hydroxylic nucleophiles is described

Journal ArticleDOI
TL;DR: La synthese de furannes presentee s'effectue dans l'acetonitrile par traitement d'allenals et d'allsenones avec AgNO 3 ou AgBF 4 as discussed by the authors.
Abstract: La synthese de furannes presentee s'effectue dans l'acetonitrile par traitement d'allenals et d'allenones avec AgNO 3 ou AgBF 4

Journal ArticleDOI
TL;DR: In this article, a simple synthesis of (R)-γ-caprolactone employing Sharpless asymmetric epoxidation and the presented oxidation procedure as key steps is presented. But the procedure is compatible with other functional groups except for those that are quite acid sensitive.
Abstract: The oxidation of aromatic rings to carboxylic acids with ruthenium tetraoxide is shown to be a very efficient and simple reaction using periodic acid as the stoichiometric oxidant in a biphasic solvent system (CCl 4 , CH 3 CN, H 2 O). The reaction can be very sensitive to the nature of the ring substituents when more than one aromatic ring is present. The procedure is compatible with other functional groups except for those that are quite acid sensitive. A simple synthesis of (R)-γ-caprolactone employs Sharpless asymmetric epoxidation and the presented oxidation procedure as key steps


Journal ArticleDOI
TL;DR: Treatment of C60 with osmium tetroxide and pyridine gives the osmate ester (2:1 adduct) establishing that oxygen functionality can be added to C60 without disrupting the carbon framework.
Abstract: Treatment of C60 with osmium tetroxide and pyridine gives the osmate ester (2:1 adduct) establishing that oxygen functionality can be added to C60 without disrupting the carbon framework.

Journal ArticleDOI
TL;DR: Les produits formes par photolyse directe ou photosensibilisee sont: les dimethyl-4,4'-, -2,4'- and -3,4', and les dimmethyl-2, 4'-, and 2, 4'-iodo-2-and -3-biphenyles as mentioned in this paper.
Abstract: Les produits formes par photolyse directe ou photosensibilisee sont: les dimethyl-4,4'-, -2,4'- et -3,4'- et les dimethyl-2,4'- et -3,4'-iodo-2- et -3-biphenyles

Journal ArticleDOI
TL;DR: 1,3,3-Trinitroazetidine (1) was synthesized via a Mannich condensation and its structure elucidated by X-ray crystallography as mentioned in this paper.
Abstract: 1,3,3-Trinitroazetidine (1) was synthesized via a Mannich condensation and its structure elucidated by X-ray crystallography


Journal ArticleDOI
TL;DR: The authors examine en particulier l'influence des amines sur l'oxydation du cholesterol dans les conditions du titre, and examine les amines' influence on l'oxygenation of LDL.
Abstract: On examine en particulier l'influence des amines sur l'oxydation du cholesterol dans les conditions du titre