- The Elusive Seven-Membered Cyclic Imino Ether Tetrahydrooxazepine
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Cyclic imino ether heterocycles are used as ligands in transition metal catalysis, in various drugs and as reactive monomers in living cationic ring-opening polymerization (CROP). While five- and six-membered cyclic imino ethers, i.e. 2-oxazolines and 4,5-dihydro-1,3-oxazines, have extensively been studied in these areas, their seven-membered ring counterparts have remained unexplored. Herein, we report the synthesis of 2-phenyl-4,5,6,7-tetrahydro-1,3-oxazepine allowing reassignment of the earlier, incorrectly reported 4,5,6,7-tetrahydro-1,3-oxazepines as their N-acylated pyrrolidine isomers. Finally, we also report a comparison of the CROP reactivity of a homologous series of cyclic imino ethers with a 2-carbon, 3-carbon, and 4-carbon methylene bridge, revealing a remarkable ring size effect.
- Verbraeken, Bart,Hullaert, Jan,Van Guyse, Joachim,Van Hecke, Kristof,Winne, Johan,Hoogenboom, Richard
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supporting information
p. 17404 - 17408
(2019/01/04)
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- Pd-catalysed oxidative carbonylation of amino alcohols to N,N′-bis(hydroxyalkyl)ureas under mild conditions using molecular oxygen as the oxidant
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A very simple method has been developed for the selective synthesis of symmetrical N,N′-bis(hydroxyalkyl)ureas, OC[NH-(CH2)x-OH]2 (x = 3-6), by oxidative carbonylation of α,ω-amino alcohols [3-aminopropanol (3-AP), 4-aminobutanol (4-AB), 5-aminopentanol (5-APe), 6-aminohexanol (6-AH)] with CO/O2 mixtures (O2 = 5 mol%) in the presence of Pd(II)/ligand/NEt3·HI catalytic systems. The catalytic process takes place under very mild conditions (p(CO/O2) = 0.1 MPa; 303-333 K). The target products can be isolated in high yield through a very simple and straightforward procedure. The catalytic system can be easily recovered and recycled for several times. The influence of a few reaction parameters (nature of ancillary ligand and iodide co-catalyst, I/Pd molar ratio, etc.) on the catalytic activity has also been investigated and the main mechanistic features of the catalytic process fully elucidated.
- Giannoccaro, Potenzo,Ferragina, Carla,Gargano, Michele,Quaranta, Eugenio
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experimental part
p. 78 - 84
(2010/09/06)
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- A NEW SYNTHESIS OF HETEROCYCLES VIA CARBONILATION OF AMINES WITH CARBON MONOXIDE IN THE PRESENCE OF SELENIUM
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Amines which contain a second functional group in the appropriate position react with carbon monoxide in the presence of selenium to form heterocyclic derivatives in which carbon monoxide is incorporated.For instance, diamines, aminoalcohols, and their related compounds undergo carbonylation to give cyclic ureas, urethanes and the corresponding carbonylated compounds.For diamines and amino alcohols with more than two carbon atoms between the functional groups, intermolecular carbonylative coupling takes place competing with the intramolecular reaction.High selectivity has been attained under specified reaction conditions.Anilines having cyano or acetyl groups on the ortho position afford new classes of selenium-containing heterocycles.In these reactions, carbamoselenoate has been suggested as the common key intermediate.
- Yoshida, Tohru,Kambe, Nobuaki,Ogawa, Akiya,Sonoda, Noboru
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p. 137 - 148
(2007/10/02)
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- Preparation and Thermolysis of N-Ammonioamidates Containing Hydroxyl Group in Acyl Moiety
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The title ammonioamidates (aminimides) were prepared in satisfactory yields from lactones or α-hydroxy carboxylates.By the thermolysis of these aminimides in mesitylene, some types of urethane compounds were formed, depending on the structure of the aminimide and on the concentration of the solutions.
- Masuyama, Araki,Tsuchiya, Kikuo,Okahara, Mitsuo
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p. 2855 - 2859
(2007/10/02)
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