Icelandic
Albanian
Arabic
Armenian
Azerbaijani
Belarusian
Bengali
Bosnian
Catalan
Czech
Danish
Deutsch
Dutch
English
Estonian
Finnish
Français
Greek
Haitian Creole
Hebrew
Hindi
Hungarian
Icelandic
Indonesian
Irish
Italian
Japanese
Korean
Latvian
Lithuanian
Macedonian
Mongolian
Norwegian
Persian
Polish
Portuguese
Romanian
Russian
Serbian
Slovak
Slovenian
Spanish
Swahili
Swedish
Turkish
Ukrainian
Vietnamese
Български
中文(简体)
中文(繁體)
Journal of Organic Chemistry 2004-Jul

Syn-anti isomerization of aldols by enolization.

Aðeins skráðir notendur geta þýtt greinar
Skráðu þig / skráðu þig
Krækjan er vistuð á klemmuspjaldið
Dale E Ward
Marcelo Sales
Pradip K Sasmal

Lykilorð

Útdráttur

A variety of aldol adducts are shown to undergo efficient syn-anti isomerization in the presence of imidazole by an enolization mechanism. Isomerizations are high yielding and occur with little or none of the usual byproducts arising from competing elimination or retroaldol reactions. Most substrates reach equilibrium within 0.3-3 days at ambient temperature in chloroform, benzene, or dichloromethane containing 0.3-1 M imidazole. The process is particularly facile for aldols derived from tetrahydro-4H-thiopyran-4-one with rate constants for equilibration varying over ca. 1 order of magnitude for the adducts studied; structurally related aldols derived from cyclohexanone isomerized ca. 3-4 times slower. Isomerization of the acyclic aldol 5-hydroxy-4-methyl-5-phenyl-3-pentanone required heating to 60 degrees C but was achieved with minimal (<5%) retroaldol or elimination. A methoxymethyl ether derivative isomerized 30-40 times slower than the parent aldol. Isomerization of alpha,alpha'-disubstituted aldols and alpha,alpha'-bisaldols indicated low regioselectivity in the enolization. The synthetic utility of the process was demonstrated with the effective preparation of aldol stereoisomers unobtainable by direct methods.

Skráðu þig á
facebook síðu okkar

Heillasta gagnagrunnur lækningajurtanna sem studdur er af vísindum

  • Virkar á 55 tungumálum
  • Jurtalækningar studdir af vísindum
  • Jurtaviðurkenning eftir ímynd
  • Gagnvirkt GPS kort - merktu jurtir á staðsetningu (kemur fljótlega)
  • Lestu vísindarit sem tengjast leit þinni
  • Leitaðu að lækningajurtum eftir áhrifum þeirra
  • Skipuleggðu áhugamál þitt og vertu vakandi með fréttarannsóknum, klínískum rannsóknum og einkaleyfum

Sláðu inn einkenni eða sjúkdóm og lestu um jurtir sem gætu hjálpað, sláðu jurt og sjáðu sjúkdóma og einkenni sem hún er notuð við.
* Allar upplýsingar eru byggðar á birtum vísindarannsóknum

Google Play badgeApp Store badge