- A calorimetric investigation to safely scale-up a curtius rearrangement of acryloyl azide
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N-Vinyl-O-benzyl urethane was prepared for use as a starting material in a multistep synthesis of a drug candidate. After unsuccessful attempts to employ non-Curtius options to prepare this intermediate, we decided to assess the thermodynamic and kinetic parameters of the acyl azide Curtius rearrangement and trapping of the intermediate isocyanate. (Prepared in analogy to the literature method of Hegedus et al.: Wieber, G. M.; Hegedus, L. S.; Akermark, B.; Michalson, E. T. J. Org. Chem. 1989, 54, 4649-4653.) Reaction calorimetry was utilized to show that the rate of the Curtius rearrangement was completely dose-rate controlled, and that under carefully defined conditions this reaction could be safely performed on limited scale. In addition to addressing the thermal hazard issues, profiling the reaction with reaction calorimetry and interfaced technologies resulted in significant process improvements.
- Amende, David J.,DeVries, Keith M.,Clifford, Pamela J.,Brenek, Steven J.
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- Synthesis of vinylisocyanate
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N-1-chloroethylcarbamoyl chloride 3 is generated by selective photohalogenation of ethylisocyanate 2 (or carbamoyl chloride). On dehydrohalogenation with suitable aliphatic isocyanates or with N,N-dimethylacetamide vinylisocyanate 6 is obtained in good yields.
- Konig
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- One-pot synthesis of ureas from Boc-protected amines
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A practical one-pot synthesis of ureas is described. Boc-protected amines can be transformed into nonsymmetrical and symmetrical disubstituted and trisubstituted ureas utilizing 2-chloropyridine and trifluoromethanesulfonyl anhydride for the in situ generation of an isocyanate, which reacts with an amine. A variety of amines can be employed successfully, leading to high yields of isolated ureas.
- Spyropoulos, Constantinos,Kokotos, Christoforos G.
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p. 4477 - 4483
(2014/06/09)
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- METHOD FOR PRODUCING ACRYLOYL AZIDE
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PROBLEM TO BE SOLVED: To provide a method for easily and efficiently producing an acryloyl azide from acrylic acid which may have a substituent at an α-carbon atom or its acid anhydride, and a method for easily and efficiently producing an N-vinylisocyanate and an N-vinylcarbamate from the acryloyl azide. SOLUTION: The method for producing the acryloyl azide is to react the acrylic acid which may have a substituent on the α-carbon atom or its acid anhydride with an azide compound. The method for producing the N-vinyl carbamate is to perform a rearrangement reaction of the acryloyl azide to obtain the N-vinylisocyanate which is reacted with an alcohol.
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Page/Page column 16; 17
(2008/06/13)
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- Nonacyclic nodulisporic acid derivatives
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The present invention relates to novel nodulosporic acid derivatives, which are acaricidal, antiparasitic, insecticidal and anthelmintic agents.
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- Preparation of alk-1-enyl isocyanates
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Alk-1-enyl isocyanates are prepared by reacting a 1-haloalkylcarbamyl halide and/or a 1-haloalkyl isocyanate with a carboxamide, and are useful starting materials for the preparation of pesticides, dyes, drugs, textile water-repellents, detergents, plastics, bleaches and adhesives.
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- Preparation of 1-haloalkyl isocyanates and 1-alkenyl isocyanates
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1-Haloalkyl isocyanates and 1-alkenyl isocyanates are prepared by reacting 1-haloalkylcarbamic acid halides or 1-haloalkyl isocyanates with α-pinene. The 1-alkenyl isocyanates and 1-haloalkyl isocyanates obtained according to the invention are valuable starting materials for the preparation of pest control agents, dyes, drugs, water-repellent textile finishes, detergents, plastics, bleaches and adhesives.
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