Relative reactivity and stereoselectivity in the Wittig reactions of substituted benzaldehydes with benzylidenetriphenylphosphorane

Yamataka, Hiroshi; Nagareda, Katsushi; Ando, K.; Hanafusa, Terukiyo

doi:10.1021/jo00036a021

Cited by 59 publications

(58 citation statements)

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“…cis‐ 4‐Chlorostilbene was obtained as a colorless oil in 72 % yield. Spectral data obtained for this compound corresponded to previously reported data . 1 H NMR (300.13 MHz, C 6 D 6 , 25 °C): δ =6.25 (d, J =12.3 Hz, 1 H, CH=CH), 6.41 (d, J =12.3 Hz, 1 H, CH=CH), 6.93–7.13 ppm (m, 9 H, CH Ar ); 13 C NMR (75.49 MHz, C 6 D 6 , 25 °C): 127.6 (s, CH Ar ), 128.7 (s, CH Ar ), 128.8 (s, CH Ar ), 129.1 (s, CH Ar ), 129.2 (s, CH=CH), 130.6 (s, CH Ar ), 131.2 (s, CH=CH), 133.2 (s, C Ar ), 135.9 (s, C Ar ), 137.2 ppm (s, C Ar ).…”

Section: Methodssupporting

confidence: 86%

Donor/Acceptor‐Stabilized 1‐Silaketene: Reversible [2+2] Cycloaddition with Pyridine and Evolution by an Olefin Metathesis Reaction

Reyes

Troadec

Rodrı́guez

et al. 2016

Chemistry A European J

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The reaction of silacyclopropylidene 1 with benzaldehyde generates a 1-silaketene complex 2 by a formal atomic silicon insertion into the C=O bond of the aldehyde. The highly reactive 1-silaketene 2 undergoes a reversible [2+2] cycloaddition with pyridine to give sila-β-lactam 3. Of particular interest, in the presence of 4-dimethylaminopyridine (DMAP), 1-silaketene complex 2 evolves through an intramolecular olefin metathesis reaction, generating a new 1-silaketene complex 8 and cis-stilbene. Theoretical studies suggest that the reaction proceeds through the formation of a transient silacyclobutanone, a four-membered-ring intermediate, similar to that proposed by Chauvin and co-workers for the transition-metal-based olefin metathesis.

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Section: Methodssupporting

confidence: 86%

Donor/Acceptor‐Stabilized 1‐Silaketene: Reversible [2+2] Cycloaddition with Pyridine and Evolution by an Olefin Metathesis Reaction

Reyes

Troadec

Rodrı́guez

et al. 2016

Chemistry A European J

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“…Strong orthoeffects from substituents on phosphorus were already well known through the work of McEwen and co-workers 75, 76 and these had been extended to the Wittig reaction, although with conflicting results. 77,78 It was also known that Z-selectivity in stilbene synthesis could be induced by ortho-substituents with heteroatom lone pairs on the aldehyde 79,80 However, remarkably, we found that this latter Z-selectivity could be substantially augmented by an additional ortho-substituent on the benzylide, despite the fact that such a substituent would ordinarily lead to E-selectivity. This counter-intuitive cooperative effect was strong enough to be preparatively useful (Z/E up to 95:5) and the resulting Z-2,2'-disubstituted stilbenes have been used to good effect in synthesis by others.…”

Section: Our Interest In This Areamentioning

confidence: 56%

“…We rationalize the signature aldehyde -heteroatom effect within the transition state model for the [2+2] cycloaddition mechanism 38 with the single additional proposal of the existence of a stabilizing phosphorus-heteroatom bonding interacction 66,79 in the cisselective cycloaddition TS (see Figure 3). This results in a 3-centre-4-electron bond, with the acceptor orbital being one of the P-C bond * orbitals, analogous to the (orthogonal) interaction forming the P-O bond.…”

Section: Rationalization Of the Effects Within The Cycloaddition Mechmentioning

confidence: 61%

Unequivocal Experimental Evidence for a Unified Lithium Salt-Free Wittig Reaction Mechanism for All Phosphonium Ylide Types: Reactions with β-Heteroatom-Substituted Aldehydes Are Consistently Selective for cis-Oxaphosphetane-Derived Products

Byrne

Gilheany

2012

J. Am. Chem. Soc.

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ABSTRACT:The true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized and stabilized): there is consistently raised selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving ald ehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom su bstituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all lithium salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a co-operative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides, and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.

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“…[25] Prescreening of different solvents (Supporting Information, Figure S3) indicated that in biobased 2Me-THF [26] the reaction was extremely effective both in terms of conversion and selectivity,n otwithstandingt hat 1 is only sparingly soluble in all the tested solvents. [25] Prescreening of different solvents (Supporting Information, Figure S3) indicated that in biobased 2Me-THF [26] the reaction was extremely effective both in terms of conversion and selectivity,n otwithstandingt hat 1 is only sparingly soluble in all the tested solvents.…”

mentioning

confidence: 99%

Methyltriphenylphosphonium Methylcarbonate, an All‐In‐One Wittig Vinylation Reagent

et al. 2015

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The methyltriphenylphosphonium methylcarbonate salt [Ph3 PCH3 ][CH3 OCO2 ], obtained directly by quaternarization of triphenylphosphine with dimethylcarbonate, is a latent ylide that promotes Wittig vinylation of aldehydes and ketones. Alkenes are obtained simply by mixing [Ph3 PCH3 ][CH3 OCO2 ] and the carbonyl and heating in a solvent (no base, no halides, and no inorganic byproducts). Deuterium exchange experiments and the particularly short anion-cation distance measured by XRD in [Ph3 PCH3 ][CH3 OCO2 ] allowed to explain the nature and reactivity of this species. Green chemistry metrics (atom economy, mass index, environmental factor) indicate that this vinylation procedure is more efficient than comparable ones. Deuterated [Ph3 PCD3 ][CH3 OCO2 ] promoted the synthesis of deuterated olefins.

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Relative reactivity and stereoselectivity in the Wittig reactions of substituted benzaldehydes with benzylidenetriphenylphosphorane

Cited by 59 publications

References 0 publications

Donor/Acceptor‐Stabilized 1‐Silaketene: Reversible [2+2] Cycloaddition with Pyridine and Evolution by an Olefin Metathesis Reaction

Donor/Acceptor‐Stabilized 1‐Silaketene: Reversible [2+2] Cycloaddition with Pyridine and Evolution by an Olefin Metathesis Reaction

Unequivocal Experimental Evidence for a Unified Lithium Salt-Free Wittig Reaction Mechanism for All Phosphonium Ylide Types: Reactions with β-Heteroatom-Substituted Aldehydes Are Consistently Selective for cis-Oxaphosphetane-Derived Products

Methyltriphenylphosphonium Methylcarbonate, an All‐In‐One Wittig Vinylation Reagent

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