A Practical Method for the Preparation of Nitriles from Primary Amides Under Non-Acidic Conditions

Bose, D. Subhas; Jayalakshmi, B.

doi:10.1055/s-1999-3695

Cited by 30 publications

(15 citation statements)

References 3 publications

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“…As trimethylsilylperrhenate and rhenium( VII ) oxide are very moisture‐sensitive and highly expensive compounds, we chose aqueous perrhenic acid (which is easy to handle and less expensive than trimethylsilylperrhenate) as a practical dehydration catalyst. Interestingly, dibutyltin oxide was almost inert under the same conditions (Table 1, entry 10) 3c,d…”

Section: Dehydration Of 4‐phenylbutyramide Catalyzed By Metal Compoundsmentioning

confidence: 89%

“…In this reaction, acetamide is produced instead of water. In 1999, Bose et al3c,d reported the first catalytic dehydration of primary amides in the absence of any additives except for catalyst. Unfortunately, this method requires a large amount of highly toxic dibutyltin oxide (25–35 mol3c or 37 mol %3d) as a catalyst.…”

Section: Dehydration Of 4‐phenylbutyramide Catalyzed By Metal Compoundsmentioning

confidence: 99%

“…The reaction of 3‐ethylhexanamide was carried out in toluene in the presence of trimethylsilylperrhenate (10 mol %) because the boiling point of the corresponding nitrile is close to that of mesitylene (Table 3, entry 3). The use of dibutyltin oxide instead of perrhenic acid under the same conditions gave poor results, even in mesitylene (Table 3, entry 6) 3c,d. Anisole was effective as a solvent for the reaction of a less soluble amide (1‐naphthalenecarboxamide; Table 3, entry 8).…”

Section: Dehydration Of 4‐phenylbutyramide Catalyzed By Metal Compoundsmentioning

confidence: 99%

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Rhenium(VII) Oxo Complexes as Extremely Active Catalysts in the Dehydration of Primary Amides and Aldoximes to Nitriles

2002

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The synthetic importance of the dehydration of primary alkyl or aryl amides to their corresponding nitriles has been thoroughly documented in the literature. [1, 2] Many of these reported methods, however, require the use of stoichiometric or excess amounts of highly reactive reagents or harsh conditions in acidic or basic media, or they involve tedious workup procedures. More recently, several methods for dehydration of primary amides under milder conditions have been developed. [3] In 1990, Watanabe et al. [3a] found that dichlorotris(triphenylphosphane)ruthenium (1 mol %) catalyzes the dehydration of primary amides in the presence of urea derivatives (1 equiv) in diglyme at 180 8C. In 1996, Mioskowski and co-workers [3b] developed the paraformaldehyde-catalyzed (490 mol %) water-transfer reaction of primary amides in a formic acid/acetonitrile mixture. In this reaction, acetamide is produced instead of water. In 1999, Bose et al. [3c,d] reported the first catalytic dehydration of primary amides in the absence of any additives except for catalyst. Unfortunately, this method requires a large amount of highly toxic dibutyltin oxide (25±35 mol [3c] or 37 mol % [3d] ) as a catalyst.In our continued studies on the development of various catalytic dehydration reactions in the absence of any additives except for catalyst, such as direct amide condensation, [4] direct ester condensation, [5] and dehydration of alcohols to alkenes, [6] we were interested in nitrile synthesis by catalytic dehydration reactions. We describe herein rhenium(vii) oxo complexes [7 8] as extremely active catalysts (1 mol %) for dehydration of not only primary amides but also of aldoximes to the corresponding nitriles.We first investigated the catalytic activities (10 mol %) of various metal salts, metal alkoxides, metal oxides, and organometallic compounds that promote the model reaction of 4-phenylbutyramide in toluene at azeotropic reflux (120 8C) with removal of water (Dean±Stark apparatus) for 16 hours (Table 1). Commercially available trimethylsilylperrhenate [9] was the most effective catalyst for this reaction (Table 1, entry 1), and a 65±70 wt % aqueous solution of perrhenic acid [9] and rhenium(vii) oxide [9] exhibited higher catalytic activities than other metal compounds (Table 1, entries 2 and 4). When the temperature was raised from 120 8C to 1258C, the perrhenic acid catalyzed conversion into the corresponding nitrile was increased from 38 % to 78 % (Table 1, entry 3), whereas rhenium(vi) and rhenium(iv) oxides were inert (Table 1, entries 12 and 13). As trimethylsi-lylperrhenate and rhenium(vii) oxide are very moisturesensitive and highly expensive compounds, we chose aqueous perrhenic acid (which is easy to handle and less expensive than trimethylsilylperrhenate) as a practical dehydration catalyst. Interestingly, dibutyltin oxide was almost inert under the same conditions (Table 1, entry 10). [3c,d] We next investigated the solvent effect on the dehydration reaction of 4-phenylbutyramide catalyzed by aqueous perrhen...

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Section: Dehydration Of 4‐phenylbutyramide Catalyzed By Metal Compoundsmentioning

confidence: 89%

Section: Dehydration Of 4‐phenylbutyramide Catalyzed By Metal Compoundsmentioning

confidence: 99%

Section: Dehydration Of 4‐phenylbutyramide Catalyzed By Metal Compoundsmentioning

confidence: 99%

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Rhenium(VII) Oxo Complexes as Extremely Active Catalysts in the Dehydration of Primary Amides and Aldoximes to Nitriles

2002

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“…[38] We hypothesized that 2-ClPyr could be used as a Et 3 N substitute for in situ formation of nitriles from primary amides, while selectively activating a secondary amide. Interestingly, cyclohexanecarboxamide 84 was used as a cyclohexanecarbonitrile surrogate to give quinazoline 76 in 74 % yield (Scheme 25) in a single step by direct condensation.…”

Section: Alternative Strategiesmentioning

confidence: 99%

New Strategies for the Synthesis of Pyrimidine Derivatives

Hill

Movassaghi

2008

Chemistry A European J

129

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Recent advances in pyrimidine synthesis are described. Modification of conventional strategies involving N-C-N fragment condensation with 1,3-dicarbonyl derivatives remains a common theme in current literature. Other methods, including N-C fragment condensation strategies, provide reactive intermediates capable of intramolecular cyclization and formation of pyrimidine derivatives. These recently developed methodologies offer a valuable addendum to azaheterocycle synthesis.

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“…As dehydration reagents, phenyl chloroformate [28], phenyl chlorothionoformate [29], oxalyl chloride/DMSO [30], triflic anhydride [31], and the Burgess reagent [32] The reactions with the two chloroformates require rather long reaction times (6-10 h), whereas those with triflic anhydride, under Swern conditions, and with the Burgess reagent are complete within 0.3-2 h. With the exception of the Burgess reagent, which is a solid (mp 80 C), all the other reagents are highly toxic liquids (the toxicity of chloroformates is similar to that of phosgene; see Table 3.4, Chapter 3), particularly oxalyl chloride, which is also volatile (bp 63 C). As dehydration reagents, phenyl chloroformate [28], phenyl chlorothionoformate [29], oxalyl chloride/DMSO [30], triflic anhydride [31], and the Burgess reagent [32] The reactions with the two chloroformates require rather long reaction times (6-10 h), whereas those with triflic anhydride, under Swern conditions, and with the Burgess reagent are complete within 0.3-2 h. With the exception of the Burgess reagent, which is a solid (mp 80 C), all the other reagents are highly toxic liquids (the toxicity of chloroformates is similar to that of phosgene; see Table 3.4, Chapter 3), particularly oxalyl chloride, which is also volatile (bp 63 C).…”

Section: -Cyanopyridine 23mentioning

confidence: 99%

Evaluation of Phosgenation Reactions

Cotarca

Eckert

2003

Phosgenations ‐ a Handbook

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A Practical Method for the Preparation of Nitriles from Primary Amides Under Non-Acidic Conditions

Abstract: In order to establish a mild conversion method of primary amides to nitriles, various types of carboxamides were treated with trifluoromethanesulfonic anhydride and triethylamine, as a dehydrating agent to obtain the desired nitriles in 84Ð95% yields.

Cited by 30 publications

References 3 publications

Rhenium(VII) Oxo Complexes as Extremely Active Catalysts in the Dehydration of Primary Amides and Aldoximes to Nitriles

Rhenium(VII) Oxo Complexes as Extremely Active Catalysts in the Dehydration of Primary Amides and Aldoximes to Nitriles

New Strategies for the Synthesis of Pyrimidine Derivatives

Evaluation of Phosgenation Reactions

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