Additionen an die Dreifachbindung, V. Der sterische Verlauf von Additionen an die Dreifachbindung

Winterfeldt, Ekkehard; Preuß, H.

doi:10.1002/cber.19660990212

Cited by 143 publications

(41 citation statements)

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“…The product ratio (4b : 106 r 7 : 3) is consistent with that observed by Winterfeldt for the same reaction catalyzed by N-methyl morpholine (3 (14), and 4b (3) have all been reported previously.…”

Section: Mechanismssupporting

confidence: 90%

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The Reaction of Propiolic Acid Esters with Tertiary Amines. Formation of Betaines

Mcculloch¹,

McInnes²

1974

Can. J. Chem.

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Section: Mechanismssupporting

confidence: 90%

“…Tertiary alkylamines are widely used as catalysts for nucleophilic additions to acetylenic esters (1)(2)(3)(4) and are also useful as polymerization catalysts (5,6). Catalyzed dimerization of a propiolate ester H-CrC-C0,R can be effected readily.…”

Section: Introductionmentioning

confidence: 99%

The Reaction of Propiolic Acid Esters with Tertiary Amines. Formation of Betaines

Mcculloch¹,

McInnes²

1974

Can. J. Chem.

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“…The more likely pre-ionization step of reaction 141, could result in second order kinetics, first order in each of the starting materials, if addition of the arsine anion to the butyne is slower than the reverse step of reaction [4]. However, this pre-ionization step is not likely to contribute significantly to the overall mechanism of the addition reaction since the maximum rate of exchange of the label of diethylarsine with dimethylarsenic deuteride, regardless of mechanism, is lo3 times slower than the rate of the addition reaction (1 1).…”

Section: Reaction Mechanismmentioning

confidence: 99%

“…The mechanism suggested for these 1 cis additions involves an intramolecular proton , transfer (4). In general, the steric course of the reaction seems to depend on many variables such ' as the nature of the alkyne and amine (3), and the solvent (5,6).…”

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confidence: 99%

Kinetics and mechanism of the addition of dimethylarsine to hexafluorobutyne-2

Cullen¹,

Leeder²

1969

Can. J. Chem.

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The addition of dimethylarsine to hexafluorobutyne-2 follows second order kinetics with activation energy, 6.09 k 0.20 kcallmole, and activation entropy, -48 k 1 e.u. The product distribution of the competitive reaction of din~ethylarsenic deuteride and diethylarsine with the acetylene shows that the addition mainly involves an intermolecular proton transfer. The mechanism of the addition is discussed.Canadian Journal of Chemistry, 47, 2137 (1969) Many investigations have been made of nucleophilic additions to acetylenes and a general rule of "trans addition" was postulated by Truce and Simms (1) and independently by Miller (2). This rule of stereospecific trans addition was based on product configuration. However, recently cis addition products have also been isolated (3, and references therein), mainly from reactions of primary and secondary amines, and with this 1 discovery, the question of the mechanism of . This reaction is clearly related to the amine additions and the present investigation was undertaken to establish if the mechanism of the arsine reaction involved a nucleophilic addition to form both products. It was also important to establish whether the hydrogen atom is transferred inter-or intra-molecularly. Experimental magnetic resonance (n.n~.r.) spectra were run on Varian A-60 and HA-100 instruments and are reported in p.p.m. downfield from external TMS. Ultraviolet (u.v.) spectra were recorded using a Cary Model 14 spectrophotometer; this was also used for the kinetic studies. Infrared (i.r.) spectra were run on a Perkin-Elmer Model 457 instrument. Prepamtion of Di~netl~ylarsit~eThe method used is a modification of that of Dehn and Wilcox (8). A 1-liter 3-necked flask was fitted with a dropping funnel, water-cooled condenser, stirrer, nitrogen purge, and cold traps (-196') to condense any volatile productscoming through the condenser. Mercuric chloride (30 g) and zinc dust (290 g) were placed in the flask and stirred vigorously with 100 ml of water. A solution of dimethylarsinic acid (50 g) in water (100 ml) was purged with nitrogen, transferred to the dropping funnel using a syringe, and combined with the slurry in the reaction flask. In a similar way 12 N hydrochloric acid (250 ml) was slowly added to the vigorously stirred flask. After 6 h, the contents of the traps were taken into the vacuum system and dried over PZO,. The yield of dimethylarsine was 34.1 g (89%). It had a very strong As-H stretching frequency at 2085 cm-' and the n.ni.r. spectrum showed a doublet at 0.82 p.p.m. (6H) and a septet a t 2.82 p.p.m. (IH) ( J C H~H = 7.0 HZ). Prepnrrrtiotz of Dimetl~ylnrse~~ic DeuterideDimethylarsine (10.8 g) was shaken with D 2 0 (30 g) and a trace of HCI (to speed exchange) for one week in a sealed tube. The arsine was separated and re-equilibrated with fresh D 2 0 . This yielded a product which is -100% (CH3),AsD as detected by n.ni.r.; (1 :1:1 triplet a t 0.82 p.p.m. ( J C H 3~ = 1 HZ)). The i.r. spectrum showed a strong As-D stretching band at 1502 cm-'.Volatile reagents and products wer...

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“…Addition of alcohol 8 to methyl propiolate in the presence of N-methylmorpholine [8] afforded the close proximity with H 9Јax . In the same way, in 13, Me 6Јeq displayed a significant NOE with H 7Јax and H 7Јeq whereas (E)-β-alkoxyacrylate 9.…”

mentioning

confidence: 95%

Silicon-Controlled Intramolecular Thermal H-Ene Reaction – A New Access to a Key Intermediate of (±)-cis-γ-Irone

Monti¹,

Laval

Feraud

1999

Eur. J. Org. Chem.

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The primordial influence of the silyl group in an intramolecular thermal H‐ene reaction is reported. The silyl group lowered the energy of the transition state and allowed the reaction to proceed at a lower temperature than that of the simple all‐carbon analog, thereby excluding the formation of undesirable by‐products. This sequence has been applied for new access to a key intermediate in the diastereoselective synthesis of (±)‐cis‐γ‐irone with high chemocontrol and significantly improved overall yield.

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Additionen an die Dreifachbindung, V. Der sterische Verlauf von Additionen an die Dreifachbindung

Abstract: Der sterische Verlauf der Addition von Aininen uiid Alkoholen an die Dreifachbindung unter den verschiedenen Bedingungen wird untersucht, wobei sich zeigt, daD sekundare Amine stereospezifisch cis-Additionsprodukte liefern.

Cited by 143 publications

References 15 publications

The Reaction of Propiolic Acid Esters with Tertiary Amines. Formation of Betaines

The Reaction of Propiolic Acid Esters with Tertiary Amines. Formation of Betaines

Kinetics and mechanism of the addition of dimethylarsine to hexafluorobutyne-2

Silicon-Controlled Intramolecular Thermal H-Ene Reaction – A New Access to a Key Intermediate of (±)-cis-γ-Irone

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