Die Chemie der Dichlormethylen‐ammoniumsalze („Phosgen‐Imoniumsalze”︁)

Viehe, H. G.; Janousek, Z.

doi:10.1002/ange.19730851902

Cited by 51 publications

(7 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…dition of cyclopentadiene and phenyl(trifluoromethanesulfonyl)acetylene occurs readily at room temperature whereas phenylpropioloyl chloride undergoes no appreciable reaction with cyclopentadiene.2 Since an acid chloride substituent on acetylenes and olefins is more activating in cycloadditions than a nitrile, aldehyde, or ester, in that order,2'9 it can be thus stated that N,iV-dimethyl-0-ethylphenylpropiolamidium tetrafluoroborate (6) reacts faster than any of the corresponding carbonyl functionalized phenylacetylenes, and the amidium group activates more strongly than an acid chloride, nitrile, aldehyde, or ester group.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and cycloaddition reactions of acetylenic iminium compounds

Baum¹,

Viehe²

1976

J. Org. Chem.

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

Synthesis and cycloaddition reactions of acetylenic iminium compounds

Baum¹,

Viehe²

1976

J. Org. Chem.

View full text Add to dashboard Cite

“…It therefore became necessary to develop an alternative method for epoxidation, and an indirect procedure eventually proved best (15 was treated with Viehe's salt (phosgene iminium chloride) (18) With respect to cleavage of the epoxides, Parker and Babine and triethylamine in refluxing 1,2-dichloroethane. Two isomers (19) had shown that dimethylmagnesium was a preferred were formed in -16:l ratio, a result that is in keeping with reagent for opening 2,3-epoxides having the a-D-mnnno confithe proposed cyclic iminium carbonate intermediate 11, which guration.…”

mentioning

confidence: 99%

Controlled formation of dipyranoside derivatives through C6 and O4. Pyranosidic homologation. VII

Molino¹,

Fraser‐Reid²

1987

Can. J. Chem.

View full text Add to dashboard Cite

. Can. J. Chem. 65,2834Chem. 65, (1987. A procedure has been developed for pyranosidic homologation of methyl a-D-glucopyranoside via C4 and C6. Reaction of the aldehydo group of compound 2 with the Wittig-Bestmann reagent, Ph3P=CHCH(OEt)2, gave an E / Z mixture of acetals, 4, which cyclizes under the specific catalysis of pyridinium p-toluenesulfonate and in the presence of alcohols to give anomerically pure olefinic bipyranosides, 6a-d. A general procedure for epoxidation of the latter involves osmium tetroxide hydroxylation, followed by reaction with phosgene iminiumchloride (Viehe's salt) to give chlorocarbamates 12 and 13, which are then subjected to the action of sodium methoxide. This allows for the formation of a single series of diastereomeric epoxides, 7, and controlled cleavage of the latter with nucleophiles then follows well-established precedents. Selective access to the "ends" of the bipyranosides 7c and d can be obtained by oxidative removal of the activated benzyl glycosides with DDQ.BRUCE FRANCIS MOLINO et BERT FRASER-REID. Can. J. Chem. 65,2834Chem. 65, (1987 (7); un clivage selectif de ces demiers a I'aide de nuclCophiles se produit en suivant les precedents bien Ctablis. On peut acceder d'une fa~on stlective aux aboutsn des bipyrannosides 7c et 7d en proctdant un enltvement oxydatif des glycosides de benzyle actives par du DDQ.[Traduit par la revue]In an effort to extend the range of simple sugar derivatives to accommodate increased numbers of contiguous chiral centers, we have developed a process termed pyranosidic homologation in which a "satellite" pyranose ring is appended to a "primary" ring (1). The assembly obtained thereby provides additional stereogenic centers, which can be manipulated according to well-precedented transformations from the carbohydrate literature. This principle is illustrated in Chart l for the bipyranose I, whose substituents, X and Y, can be introduced into I1 by taking advantage of the highly developed chemistry of unsaturated sugars (2, 3). The efficient formation of bipyranose I1 from a monopyranose precursor, 111, is an obvious first step. In this manuscript, we give details of our studies related to the transformations I11 -+ I1 -+

show abstract

“…+ 15.59" (unverdunnt)), wurde nach [61 mit p-Toluolsulfonylchlorid zu (R)- (2) umgesetzt; Fp des Rohprodukts: 20-25 "C.…”

unclassified

“…(S)-(Su): Zu einer nach [ ' I hergestellten Losung aus 6.79 g CuI in 15 ml Ether und 71.3 mmol CH3Li in 40 ml Ether wurden bei -35 "C 7.25 g (2) in 35 ml Ether gegeben. Innerhalb 1 h erwarmte man auf 0 "C und ruhrte noch 12 h. Nach Hydrolyse mit gesattigter NH4C1-Losung wurde mehrfach ausgeethert, die etherische Losung getrocknet und destilliert; Ausbeute 2.31 g (70%) (2a), LYE= +19.2" (c=0.8 g/100 ml, Methanol).…”

unclassified

See 1 more Smart Citation

Synthese carbo- und heterocyclischer π-Elektronensysteme mit pentafulvenoiden Chlorformamidinium-chloriden

Häfner

Krimmer

1980

Angew. Chem.

View full text Add to dashboard Cite

Das Edukt (R)-(2) ist leicht in 100 g-Mengen aus Diisopropylidenmannit zuganglich, dessen Herstellung['] verbessert werden konnte. Das aus (2) und Methyllithium/Kupfer(I)iodid gewonnene 1,2-Butandiol-Derivat (2a) wurde direkt rnit Bromwasserstoff/Eisessig[21 in das Gemisch der Bromalkylacetate (3u)/(4a) umgewandelt, aus dem durch Eliminierung 1,2-Epoxybutan (5a) entstand. Der Drehwert von (5a) stimmte mit dem Literatur~ert[~I fur optisch reines (S)-(Su) uberein. Analog wurde optisch reines (S)-l,Z-Epoxyheptan (5b) hergestelltf4'. Beim Schritt (2) 4 (2b) gab Variante hohere Ausbeuten (67%) als Variante A (43%) (Schema 1).

show abstract

Die Chemie der Dichlormethylen‐ammoniumsalze („Phosgen‐Imoniumsalze”︁)

Cited by 51 publications

References 67 publications

Synthesis and cycloaddition reactions of acetylenic iminium compounds

Synthesis and cycloaddition reactions of acetylenic iminium compounds

Controlled formation of dipyranoside derivatives through C6 and O4. Pyranosidic homologation. VII

Synthese carbo- und heterocyclischer π-Elektronensysteme mit pentafulvenoiden Chlorformamidinium-chloriden

Contact Info

Product

Resources

About