ChemInform Abstract: Studies on the Wittig Reaction. Part 15. A Direct Preparation of . omega.-Unsaturated Bromides via Solid/Liquid Transferred Wittig Reactions of ω-Bromoalkyltriphenyl Phosphonium Salts with Aldehydes.

A new application of the Wittig reaction to the preparation of olefins of low molecular weight which allows selective labelling in the vinyl or allyl positions with isotopes of hydrogen and carbon has been developed. Using the modification of the Wittig reaction introduced by E. J. Corey, in which a solution of the methylsulfinyl carbanion in dimethyl sulfoxide serves as the base, a series of olefins from C2 to C8 were synthesized. The synthesis was applied to the preparation of the following labelled compounds: 5-methylene-14C-bicyclo[2.2.1]hept-2-ene; propene-1-14C; 1-butene-1-14C; propene-1-d1; 2-methylpropene-1,1-d2; 2-methyl-d3-propene-3,3,3-d3; 2-methyl-2-butene-4,4,4-d3; 2-methyl-d3-2-butene-1,1,1-d3; methylene-d2-cyclohexane. For the synthesis of carbon-labelled olefins the reaction has few limitations since the intermediates and products are isotopically stable under the reaction conditions. Deuterium-labelled olefins can be obtained from deuterated formaldehyde or β-deuterated phosphonium salts, but α-deuteroketones and aldehydes and α-deuterophosphonium salts lose the isotope to the solvent.In all the Wittig reactions, benzene was formed as a by-product in 10–15% yield. The mechanism of benzene formation is probably analogous to that proposed by Seyferth involving the decomposition of a pentacovalent phosphorous intermediate.

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Highly functionalized alkenes produced from base-free organocatalytic Wittig reactions: (E)-3-benzylidenepyrrolidine-2,5-dione, (E)-3-benzylidene-1-methylpyrrolidine-2,5-dione and (E)-3-benzylidene-1-tert-butylpyrrolidine-2,5-dione

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229616008159 ◽

2016 ◽

Vol 72 (6) ◽

pp. 504-508 ◽

Cited By ~ 1

Author(s):

Marie-Luis Schirmer ◽

Anke Spannenberg ◽

Thomas Werner

Keyword(s):

Crystal Structure ◽

Hydrogen Bonds ◽

Carbonyl Compounds ◽

Wittig Reaction ◽

Phosphonium Salts ◽

Asymmetric Unit ◽

Free Base ◽

Fundamental Transformation ◽

Wittig Reactions ◽

Centrosymmetric Dimers

The Wittig reaction is a fundamental transformation for the preparation of alkenes from carbonyl compounds and phosphonium ylides. The ylides are prepared prior to the olefination step from the respective phosphonium salts by deprotonation utilizing strong bases. A first free-base catalytic Wittig reaction for the preparation of highly functionalized alkenes was based on tributylphosphane as the catalyst. Subsequently we developed a system employing a phospholene oxide as a pre-catalyst and trimethoxysilane as reducing agent which operates under milder conditions. The title compounds, (E)-3-benzylidenepyrrolidine-2,5-dione, C11H9NO2, (I), the methylpyrrolidine derivative, C12H11NO2, (II), and thetert-butylpyrrolidine derivative, C15H17NO2, (III), have been synthesized by base-free catalytic Wittig reactions. In the crystal of (I), molecules are linked into centrosymmetric dimersviapairs of N—H...O hydrogen bonds. Furthermore, in the crystal structure of (III), there are two molecules in the asymmetric unit, whereas in (I) and (II), only one molecule is present.

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The Phospha-Bora-Wittig Reaction

10.26434/chemrxiv.14753460 ◽

2021 ◽

Author(s):

Andryj Borys ◽

Ella Rice ◽

Gary Nichol ◽

Michael Cowley

Keyword(s):

Density Functional Theory ◽

Lewis Acid ◽

Carbonyl Compounds ◽

Density Functional ◽

Wittig Reaction ◽

Acid Base ◽

Functional Theory ◽

Direct Preparation ◽

Wittig Reactions

Here, we report the phospha-bora-Wittig reaction for the direct preparation of phosphaalkenes from aldehydes, ketones, esters, or amides. The transient phosphaborene Mes*P=B-NR2 reacts with carbonyl compounds to form 1,2,3-phosphaboraoxetanes, analogues of oxaphosphetane intermediates in the classical Wittig reaction. 1,2,3-phosphaboraoxetanes undergo thermal or Lewis acid/base-promoted cycloreversion, yielding phosphaalkenes. Experimental and density functional theory studies reveal far-reaching similarities between classical and phospha-bora-Wittig reactions.

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The Phospha-Bora-Wittig Reaction

10.26434/chemrxiv.14753460.v1 ◽

2021 ◽

Author(s):

Andryj Borys ◽

Ella Rice ◽

Gary Nichol ◽

Michael Cowley

Keyword(s):

Density Functional Theory ◽

Lewis Acid ◽

Carbonyl Compounds ◽

Density Functional ◽

Wittig Reaction ◽

Acid Base ◽

Functional Theory ◽

Direct Preparation ◽

Wittig Reactions

Here, we report the phospha-bora-Wittig reaction for the direct preparation of phosphaalkenes from aldehydes, ketones, esters, or amides. The transient phosphaborene Mes*P=B-NR2 reacts with carbonyl compounds to form 1,2,3-phosphaboraoxetanes, analogues of oxaphosphetane intermediates in the classical Wittig reaction. 1,2,3-phosphaboraoxetanes undergo thermal or Lewis acid/base-promoted cycloreversion, yielding phosphaalkenes. Experimental and density functional theory studies reveal far-reaching similarities between classical and phospha-bora-Wittig reactions.

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The synthesis of specifically metallated heterobimetallic dimeric porphyrins

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424602000841 ◽

2002 ◽

Vol 06 (11) ◽

pp. 720-736 ◽

Cited By ~ 4

Author(s):

Warwick J. Belcher ◽

Anthony K. Burrell ◽

David L. Officer ◽

David C. W. Reid ◽

Sonya M. Scott

Keyword(s):

Wittig Reaction ◽

Phosphonium Salts ◽

Complete Control ◽

Mixed Metal ◽

Wittig Reactions ◽

Porphyrin Metallation

A series of conjugated mixed metal heteroporphyrin dimers has been prepared using Wittig chemistry. They can be synthesized from a double Wittig reaction between porphyrin phosphonium salts and phthalaldehydes, or from stepwise Wittig reactions. This allows both symmetrical and unsymmetrical dimers to be prepared with complete control of porphyrin metallation.

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Formation of COOH-Ylides, and Their Reactivities and Selectivities in Wittig Reactions

Synlett ◽

10.1055/s-0037-1611958 ◽

2019 ◽

Vol 30 (03) ◽

pp. 333-337

Author(s):

Yuta Suganuma ◽

Yuichi Kobayashi

Keyword(s):

Hydrogen Exchange ◽

Wittig Reaction ◽

Phosphonium Salts ◽

Aliphatic Aldehydes ◽

Rapid Equilibrium ◽

Wittig Reactions ◽

Intramolecular Hydrogen ◽

First Time ◽

Methylene Group

Whereas two equivalents of base are typically required to prepare carboxylate (CO2 –) ylides [Ph3P+C–(H)-alk-CO2 –] (alk = alkanediyl) from carboxy (CO2H) phosphonium salts [(Ph3PCH2-alk-CO2H)+] X–, we reveal, for the first time, that carboxy ylides [Ph3P+C–(H)-alk-CO2H] can be generated with one equivalent of NaHMDS at 0 °C, and that the Wittig reaction of simple aliphatic aldehydes (1 equiv) with these carboxy ylides (1.5–2 equiv) in THF at –95 to –90 °C for one hour, then at warming temperatures to 0 °C over two hours affords (Z)-alkenoic acids. Phosphonium salts containing (CH2) n alkanediyl chains (n = 2–5) showed adequate reactivity and high Z-selectivity, whereas shorter or longer alkanediyl chains resulted in a low Z-selectivity and/or a low yield. On the basis of these results with different (CH2) n chains and that obtained with a rigid methylene group, we propose that a rapid equilibrium between Ph3PCH 2-alk-CO2 – and Ph3P+C–(H)-alk-CO2 H, through an intramolecular hydrogen exchange, accounts for the success of the Wittig reaction.

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Synthesis of 8-HEPE and 10-HDoHE in both (R)- and (S)-Forms via Wittig Reactions with COOH-Ylides

Synlett ◽

10.1055/s-0037-1611976 ◽

2019 ◽

Vol 30 (03) ◽

pp. 338-342

Author(s):

Yuta Suganuma ◽

Shun Saito ◽

Yuichi Kobayashi

Keyword(s):

Docosahexaenoic Acid ◽

Eicosapentaenoic Acid ◽

Wittig Reaction ◽

Phosphonium Salt ◽

Wittig Reactions

Wittig reactions using carboxy (CO2H) ylides derived from a carboxylic phosphonium salt and NaN(TMS)2 (NaHMDS) in a 1:1 ratio were applied to the synthesis of 8-HEPE and 10-HDoHE, which are metabolites of eicosapentaenoic acid and docosahexaenoic acid, respectively. The attempted Wittig reaction of 3-(TBS-oxy)pentadeca-4E,6Z,9Z,12Z-tetraenal with the carboxy ylide (2 equiv) derived from Br– Ph3P+(CH2)4CO2H and NaHMDS (1:1) competed with the elimination of the TBS-oxy group at C3 to give a mixture of the Wittig product and the elimination product in 45–50% and 30–40% yields, respectively. The elimination was suppressed completely by using three equiv of the carboxy ylides in THF/HMPA (7–8:1), and the subsequent desilylation gave 8-HEPE in (R)- and (S)-forms. Similarly, both enantiomers of 10-HDoHE were synthesized.

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