The wittig reaction or wittig olefination is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide often called a wittig reagent to give an alkene and triphenylphosphine oxide. When there is a substituent on the central carbon of a phosphonate, a trisubstituted alkene will be formed on reaction with an aldehyde. Because of the versatility of the reactions and the compatibility of many functional groups towards the transformations, both wittig olefination and hwe reactions are a mainstay in the arsenal of organic synthesis. The hornerwadsworthemmons hwe version of the wittig reaction focuses on the use of more stabilized phosphonate ylides 203. Here we prepared high molecular weight ketones by the hornerwadsworthemmons reaction of dimethyl2oxopropylphosphonate. Wadsworthemmons cyclopropanation reaction analysis. For more cool stories, pictures, and videos of chemistry demonstrations, click here this weeks reaction was the hwemodified wittig reaction and here between paraanisaldeyhde and triethyl phosphonoacetate.
Organic reactions in aqueous media are being developed because water is environmentally benign. Mechanism, references and reaction samples of the hornerwadsworthemmons reaction. The hornerwadsworthemmons reaction has evolved in the last years as one of the most powerful and reliable. The phosphonate substrate can be synthesized by a phospite and an. General chemistry 1 handdrawn ideas 25 materials science 3 medicinal chemistry 6 mnemonic. The etherification of alcohols or phenols and their subsequent claisen rearrangement under thermal conditions. Horner wadsworth emmons, kabachnikfields, arbuzov and michaelis reactions are considered as examples.
The wittig olefination utilizing phosphoranes and the related hornerwadsworthemmons hwe reaction using phosphonates transform aldehydes and ketones into substituted alkenes. It is an important process in modern chemistry as many useful compounds bear this motif. Hornerwadsworthemmons reagents olefination sigmaaldrich. Mechanism, references and reaction samples of the horner wadsworth emmons reaction. Saponification, followed by recrystallization of the acidified product gives nice needles of pmethoxycinnamic acid.
The journal of organic chemistry 2016, 81 4, 14161424. The hornerwadsworthemmons reaction is a modified wittig reaction for the synthesis of. The next reaction is a domino michaelhornerwadsworthemmons reaction. Hornerwadsworthemmons in 1961, wadsworth and emmons described the increased reactivity of phosphonatestabilized carbanions with aelectronwithdrawing substituents. The reaction has become a widespread standard tool in natural products total syntheses, providing access to relatively simple as well as highly complex synthetic targets. This lab was completed with a lab partner kristie chow. The bibliography includes 178 referencesthe bibliography includes 178 references i. The wittig reaction formal lab report experiment 21 the. The horner wadsworth emmons hwe version of the wittig reaction focuses on the use of more stabilized phosphonate ylides 203. This modification uses a phosphonate ester and a strong base to generate our ylide. Hwe stands for hornerwadsworthemmons organic reaction suggest new definition. Hornerwadsworthemmons, kabachnikfields, arbuzov and michaelis reactions are considered as examples.
Page 93 eselective hornerwadsworthemmons reaction of aldehydes with bis2,2,2trifluoroethylphosphonoacetic acid shigeki sano, yuka takemoto, and yoshimitsu nagao faculty of pharmaceutical sciences, the university of tokushima, shomachi, tokushima 7708505, japan email. Substituted horner wadsworth emmons reagents when there is a substituent on the central carbon of a phosphonate, a trisubstituted alkene will be formed on reaction with an aldehyde. In this study, we demonstrate a transitionmetalfree and halogenfree controlled synthesis of poly3alkylthienylene vinylene p3atv via hornerwadsworthemmons polycondensation. Preparation of allenes with a chiral phosphine oxide wittighorner reaction.
In the following article, an overview of the scope of wittig and hwe olefination. Wittig and hornerwadsworthemmons hwe olefination remains a series of powerful reactions in the tool kit of organic synthesis. This reaction is more superior to wittig reaction since the carbanion generated from phosponates is more nucleophilic and the phosphate byproducts are water soluble and can be. General characteristics the reaction between a phosphonate ylide and an aldehyde, which proceeds via mechanistic path similar to the wittig reaction to give an. Rapid onepot preparation of the sunscreen analog methyl. Ir percent yield c nmr h nmr tlc rf panisaldehyde 0. The reaction with ketones gave trisubstituted olefins with good to h. How is horner wadsworth emmons organic reaction abbreviated. Wittig and hornerwadsworthemmons hwe reactions run in combination with. The wittig reaction was discovered in 1954 by georg wittig, for which he was awarded the nobel prize in chemistry in. Recent applications of the hornerwadsworthemmons reaction to. Hwe hornerwadsworthemmons organic reaction acronymfinder. Usa home product directory chemical synthesis synthetic reagents cc bond.
Wittig reaction, horner wadsworth emmons reaction, water, green chemistry, onepot reaction, phase transfer. Transition metal catalysts and halogens are necessary for the controlled synthesis of. Hwe stands for horner wadsworth emmons organic reaction. Highly eselective solventfree hornerwadsworthemmons reaction catalyzed by dbu. The electrophilicity of the formyl group in the abtype monomer, 32ethylhexyl5formylthiophene2ylmethylphosphonic acid diethyl ester, could be. The wittig reaction allows the preparation of an alkene by the reaction of an aldehyde or ketone with the ylide generated from a phosphonium salt. If r is an electron withdrawing group, then the ylide is.
Triphenylphosphene oxide is tough to separate from your olefin product, therefore, we will use a more environmentallyfriendly synthetic approach known as, the horneremmons modification of the wittig reaction. Diethyl 2nitropentafluorosulfanylbenzylphosphonates, available by the vicarious nucleophilic substitution reaction of metaand paranitropentafluorosulfanylbenzenes and diethyl chloromethylphosphonate, undergo hornerwadsworthemmons reaction with aldehydes in the presence of potassium hydroxide in acetonitrile at ambient temperature to give e2nitro1alkenyl. A modified hornerwadsworthemmons reaction using electron withdrawing trifluoroethyl phosphonates 2 or benzhydryl phosphonates. One major milestone in this regard is the horner wadsworth emmons hwe reaction, a slightly di erent approach to the wittig reaction that is based on a modi ed wittig 1. Pdf hornerwadsworthemmons hwe reactions routinely employ. Synthesis of a 2,2bipyridyl functionalized oligovinylene. Green chemistry principles used co 2 extraction of limonene 26,27 safer solvent, use of renewable feedstocks, prevention synthesis of 1,2dibromo1,2diphenylethane 1 atom economy, less. Half a milliliter of distilled water was added to a 10 ml round bottom flask. View enhanced pdf access article on wiley online library. Wittig and hornerwadsworthemmons hwe olefination remains a series. Recent applications of the horner wadsworth emmons reaction to the synthesis current organic chemistry, 2012, vol. This definition appears somewhat frequently and is found in the following acronym finder categories.
For more cool stories, pictures, and videos of chemistry demonstrations, click here this weeks reaction was the hwemodified wittig reaction and here between paraanisaldeyhde and triethyl phosphonoacetate saponification, followed by recrystallization of the acidified product gives nice needles of pmethoxycinnamic acid funny thing, though, pmethoxycinnamic acid is supposed to be a. The aliphatic claisen rearrangement is a 3,3sigmatropic rearrangement in which an allyl vinyl ether is converted thermally to an unsaturated carbonyl compound. Developments in the wittig and hornerwadsworthemmons hweolefination of aldehydes and ketones with stabilised phosphoranes or phosphonates provide opportunities for multicomponent reactions and for reactions with greatly reduced solvent requirements. Highly eselective solventfree horner wadsworth emmons reaction catalyzed by dbu. A variation of the wittig reaction using phosphonate esters as the carbanion source a horner wadsworth emmons or wittig horner reaction proceeds efficiently in aqueous media.
Hornerwadsworthemmons reaction by lauren harris on prezi. Developments in the wittig and hornerwadsworthemmons. Wittig and horner wadsworth emmons hwe olefination remains a series of powerful reactions in the tool kit of organic synthesis. Introduction the socalled green chemistry or environmentally friendly chemistry is one of the most topical trends in modern chemistry. Wittig and horner wadsworth emmons olefination in aqueous media with and without phase transfer catalysis.
Wittig and hornerwadsworthemmons olefination in aqueous. The hornerwadsworthemmons reaction begins with the deprotonation of the phosphonate to give the phosphonate carbanion 1. Wittig and hornerwadsworthemmonsolefination reactions. Hornerwadsworthemmons reaction uwmadison chemistry.
Here we prepared high molecular weight ketones by the hornerwadsworthemmons reaction of dimethyl2oxopropylphosphonate and various aldehydes in. Emmons olefination, comprehensive organic name reactions and reagents, 14841490, 2010. If r 2 h, then intermediates 3a and 4a and intermediates 3b and 4b can interconvert with each other. Aminooxylation horner wadsworth emmons sequence for the synthesis of enantioenriched. Wittig reaction, hornerwadsworthemmons reaction, water, green chemistry. Request pdf highly eselective solventfree hornerwadsworthemmons reaction. Tandem, domino and onepot reactions involving wittig. If r is an electron withdrawing group, then the ylide is stabilized and is not as reactive as when r is alkyl. Strong bicyclic guanidine basepromoted wittig and horner. A onepot procedure can thus minimize chemical waste, save time. Firstly, the phosphonate ester is deprotonated using. Green chemistry view article online published on 09 september 20. Physical chemistry inorganic chemistry organic chemistry wittig reaction olefin formation these keywords were added by machine and not by the authors.
The geometry of the resulting alkene depends on the reactivity of the ylide. The hornerwadsworthemmons reaction has evolved in the last years as one of the most powerful and reliable method for stereocontrolled olefin synthesis. For successful reaction in planetary ball mill, an excess of glycine phosphonate 203 was required. Wittig and hornerwadsworthemmons hwe reactions run in combination with other. Highly eselective solventfree hornerwadsworthemmons. This process is experimental and the keywords may be updated as the learning algorithm improves. Synthesis of stilbene by the wittig and hornerwadsworthemmons reactions important concepts synthetic methods for making double bonds olefins phosphonium salt, ylide, phosphonate ester transition state controls wittig stereochemistry cis ring closure controls wadsworthemmons stereochemistry trans.
Supplementary material esi for green chemistry this journal. Emmons reagents can serve as precursors to 1,3dipoles for use in. The yields of di and trisubstituted alkenes from aldehydes and ketones are very high but yields of tetrasubstituted. The solventfree hornerwadsworthemmons reaction of triethyl phosphonoacetate with a variety of aldehydes was catalyzed by dbu in the presence of k2co3 to give e. This is modified wittig reaction in which carbanions generated from phosphonate esters are used instead of phosphonium ylides. A convenient procedure to effect the wittig and horner. Nucleophilic addition of the carbanion onto the aldehyde 2 or ketone producing 3a or 3b is the ratelimiting step.
Wittig and hornerwadsworthemmonsolefination reactions with. The horner wadsworth emmons reaction has evolved in the last years as one of the most powerful and reliable method for stereocontrolled olefin synthesis. Cyclopropanation refers to any chemical process which generates cyclopropane rings. Wittig reaction, the reaction of an aldehyde or ketone with a triphenyl phosphonium ylide the wittig reagent to produce an alkene and triphenylphosphine oxide, is of great use in forming carboncarbon bond between reactants. Recent applications of the hornerwadsworthemmons reaction. Supplementary material esi for green chemistry this. Recent applications of the hornerwadsworthemmons reaction to the synthesis current organic chemistry, 2012, vol.
One major milestone in this regard is the hornerwadsworthemmons hwe reaction, a slightly di erent approach to the wittig reaction that is based on a modi ed wittig 1. The reaction stops at betaine, and no alkene is produced. Horner wadsworth emmons in 1961, wadsworth and emmons described the increased reactivity of phosphonatestabilized carbanions with aelectronwithdrawing substituents. H functionalization esterification free radical hydroboration ketone modified swern natural products nobel prize organic organic chemistry organocatalysis organocatalyst organometallic oxidation oxidation of alcohols palladium palladium catalyst peptides.
Andrew knight 1, 1 chemistry department, florida institute of technology, 150 west university boulevard. Hornerwadsworthemmons hwe olefination phosphonate phosphorous ylide wittig wittig reaction. Preparation of allenes with a chiral phosphine oxide wittig horner reaction. The mechanism is thus greatly different to that of its carbon analogue, that is, the. Department of chemistry, university of york, york yo10 5dd, uk. Highly selective synthesis of zunsaturated esters by. Desymmetrization of mesodicarbonyl compounds by the. Stilbenes via oncolumn oxidation of vicinal diols and horneremmons reactions inhibitors of teh wnt pathway for colon cancer repression using wadsworthemmons reactions antimalarial drug analogs against p. Eselective hornerwadsworthemmons reaction of aldehydes. Solventfree method for making olefinic amino esters 205 from an aldehyde compound and a phosphonate derivative of glycine was established by lamaty scheme 2. Usa home product directory chemical synthesis synthetic reagents cc bond formation olefination horner wadsworth emmons reagents chemistry products new chemistry products. How to do synthesis nucleophiles and electrophiles. The wittig reaction was discovered in 1954 by georg wittig, for which he was awarded the nobel prize in chemistry in 1979. The reaction of an aldehyde or ketone with a phosphonium ylide to an alkene and a phosphine oxide is known as wittig reaction or wittig olefination reaction this reaction was discovered in 1954 by georg wittig, for which he was awarded the nobel prize in chemistry in 1979.
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