Wittig reaction for alkene synthesis
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The Wittig reaction is an excellent method for the synthesis of alkenes. The entire process for the Wittig reaction normally begins with triphenylphosphine reacting with a primary halide to make a phosphonium salt. In the second step, the phosphonium salt is deprotonated with a strong base, often butyl lithium, to make a phosphonium ylide, in which a carbanion is adjacent to a positively charge phosphorous center. A resonance form with a P-C double bond is also acceptable. This ylide is called the Wittig reagent. Reaction of the Wittig reagent with a carbonyl compound (ketone or aldehyde) forms a four-membered ring oxaphosphetane intermediate, which decomposed to an alkene and a phosphine oxide. The reaction between the ylide and carbonyl is the actual Wittig reaction.
The Wittig reaction is an excellent method for the synthesis of alkenes. The entire process for the Wittig reaction normally begins with triphenylphosphine reacting with a primary halide to make a phosphonium salt. In the second step, the phosphonium salt is deprotonated with a strong base, often butyl lithium, to make a phosphonium ylide, in which a carbanion is adjacent to a positively charge phosphorous center. A resonance form with a P-C double bond is also acceptable. This ylide is called the Wittig reagent. Reaction of the Wittig reagent with a carbonyl compound (ketone or aldehyde) forms a four-membered ring oxaphosphetane intermediate, which decomposed to an alkene and a phosphine oxide. The reaction between the ylide and carbonyl is the actual Wittig reaction.
4 سال پیش
در تاریخ 1399/01/08 منتشر شده
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