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Wittig reactions are most commonly used to convert aldehydes and ketones to alkenes. [1] [2] [3] Most often, the Wittig reaction is used to introduce a methylene group using methylenetriphenylphosphorane (Ph 3 P=CH 2). Using this reagent, even a sterically hindered ketone such as camphor can be converted to its methylene derivative.
Wittig reagents are usually prepared from a phosphonium salt, which is in turn prepared by the quaternization of triphenylphosphine with an alkyl halide. Wittig reagents are usually derived from a primary alkyl halide. Quaternization of triphenylphosphine with secondary halides is typically inefficient.
Air sensitivity is a term used, particularly in chemistry, to denote the reactivity of chemical compounds with some constituent of air.Most often, reactions occur with atmospheric oxygen (O 2) or water vapor (H 2 O), [1] although reactions with the other constituents of air such as carbon monoxide (CO), carbon dioxide (CO 2), and nitrogen (N 2) are also possible.
A 1,2-Wittig rearrangement is a categorization of chemical reactions in organic chemistry, and consists of a 1,2-rearrangement of an ether with an alkyllithium compound. [1] The reaction is named for Nobel Prize winning chemist Georg Wittig. [2] [3] The intermediate is an alkoxy lithium salt, and the final product an alcohol.
This reagent reacts with a ketone or aldehyde in a Wittig reaction to give an enol ether, which can be converted to the aldehyde by acid-induced hydrolysis. The initial report of the reaction demonstrated its use on the steroid tigogenone. It was later used in the Wender Taxol total synthesis and the Stork quinine total synthesis.
The Air Quality Index has jumped up to 114 in Detroit on Thursday morning, creating unhealthy air conditions for sensitive groups.. While these levels are still far from the smoky skies we saw in ...
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An example of the aza-Wittig-reaction being utilized in organic synthesis is the synthesis of (–)-benzomalvin A. Two intramolecular aza-Wittig-reactions were used to construct the seven-membered ring and the six-membered ring in the molecule's skeleton. [1] Synthesis of (−)-Benzomalvin A via multiple aza-Wittig-reactions