wittig reaction造句

• In order to obtain the E-alkene, stabilised ylides are used or unstabilised ylides using the Schlosser modification of the Wittig reaction can be performed.
• The major limitation of the traditional Wittig reaction is that the reaction proceeds mainly via the erythro betaine intermediate, which leads to the Z-alkene.
• A reaction rate acceleration is observed in several systems when a homogeneous solvent system is rapidly evaporated in a rotavap in a vacuum, one of them a Wittig reaction.
• It can be produced by a Wittig reaction or a Tebbe reaction from cyclohexanone, or as a side product of the dehydration of 2-methylcyclohexanol into 1-methylcyclohexene.
• 6-Methylenedihydrodesoxymorphine is synthesised in two steps; first a Wittig reaction is used, reacting hydrocodone with methylenetriphenylphosphorane and an alkyl lithium reagent in diethyl ether to form 6-Methylenedihydrodesoxycodeine.
• I worked on the Wittig reaction article, and we ran into the same problem-should we include the Wittig reagent as part of that article, or as a separate article.
• No one is demanding that we remove sources for statements like the Wittig reaction, or a persons status as the Prime Minister of Luxembourg, nor is anyone forbidding you from adding one.
• In that case the reagent is " almost always " used in the Wittig reaction, yet we opted to have a separate article on the reagent because conceptually it's distinct.
• The Wittig reaction was discovered in 1954 by Georg Wittig, for which he was awarded the Nobel Prize in Chemistry in 1979 . It is widely used in organic synthesis for the preparation of alkenes.
• Unsubstituted 3-benzoxepin can be synthesized through a double Wittig reaction from " o "-phthalaldehyde with bis-( ?, ?2-triphenylphosphonium )-dimethylether-dibromide . and triphenylphosphine.
• The salt is subsequently treated with sodium hydride in dichloromethane to form a ylide . Wittig reaction of the dialdehyde given in the paper with another alkaloid in the lythracae family under high dilution conditions yielded the cyclophane.
• Some examples of reactions which form carbon carbon bonds are aldol reactions, Diels Alder reaction, the addition of a Grignard reagent to a carbonyl group, a Heck reaction, a Michael reaction and a Wittig reaction.
• PCl 3 is the precursor to triphenylphosphine for the Wittig reaction, and phosphite esters which may be used as industrial intermediates, or used in the Horner-Wadsworth-Emmons reaction, both important methods for making alkenes.
• The Wittig reaction generates the allyl vinyl ether intermediate that further participates in a Claisen rearrangement to generate the final ?, ?-unsaturated ketone or aldehyde product ( Figure " Modified Wittig-Claisen tandem reactions " ).
• The key step was a tandem process that combines Tebbe olefination ( a reaction similar to Wittig reaction ) with Claisen rearrangement ( Figure " Application of modified Wittig-Claisen tandem reactions for construction of 4-cyclooctenone structure " ).
• For the generation of the other reactive group the acetal group was removed to give aldehyde "'37 "'which was subsequently converted to the terminal alkene "'38 "'in a Wittig reaction involving methylenetriphenylphosphorane.
• In the history of the Nobel Prize in Chemistry awards have been given for the invention of specific organic reactions such as the Grignard reaction in 1912, the Diels-Alder reaction in 1950, the Wittig reaction in 1979 and olefin metathesis in 2005.
• "' Georg Wittig "'( June 16, 1897 & ndash; August 26, 1987 ) was a German chemist who reported a method for synthesis of alkenes from aldehydes and ketones using compounds called phosphonium ylides in the Wittig reaction.
• The lactone is then reduced to the lactol "'5b "'with diisobutylaluminum hydride and its liberated aldehyde reacts in a Wittig reaction with methoxymethylenetriphenylphosphine ( delivering the C8 atom ) to form enol ether "'6 " '.
• The Wittig reaction involves reaction of an aldehyde or ketone with a Wittig reagent ( or phosphorane ) of the type Ph 3 P = CHR to produce an alkene and Ph 3 P = O . The Wittig reagent is itself prepared easily from triphenylphosphine and an alkyl halide.