Stereoselective Wittig Reaction-Overview - ChemTube3D
the most commonly used method of preparation for these enamines is the acid-catalyzed condensation of a secondary amine with cyclohexanone. An example is the reaction of with cyclohexanone (eq 1). The use of a preformed -amine complex with cyclohexanone greatly decreases the reaction time while maintaining high yields.This technique is also is effective with functionalized cyclohexanones. When unsymmetrical tin(II) amides are allowed to react with cyclohexanone, good yields of enamines result., readily reacts with water or atmospheric oxygen; should be stored under dry nitrogen.
Organic Chemistry Animations Introduction - …
The intermediate cyclobutanone is then opened to give the enamino ketone, which is hydrolyzed to the 2-acylcyclohexanone.Aryl halides with a halogen activated by electron-withdrawing groups react with enamines (eq 11).Cycloadditions and annulation reactions take place when cyclohexanone enamines are allowed to react with 1-buten-3-one, 1,3-butadienephosphonate, acrolein, 1,4-diacetoxy-2-butene with , or 5-nitropyrimidine (Scheme 1).Further 2,3-(ethylenedisulfonyl)-1,3-butadiene acts as a diene in Diels-Alder reactions with enamines (eq 12).[2 + 2] Cycloaddition takes place with benzyne and (Scheme 2).Photooxygenation using singlet oxygen leads to -diketones. Use of -sulfonyloxaziridines gives -amino ketones (Scheme 3).Use of trimethylene dithiotosylate produces the dithiane of cyclohexanone (eq 13).The enamine is readily converted to cyclohexene via hydroboration (Scheme 3).
From 1-methyl Cyclohexanol Xanthate hot eliminate, or from cyclohexanone methyl bromide and magnesium reaction, after hydrolysis, eliminate water molecules.