87866-95-3Relevant academic research and scientific papers
Synthesis and crystal structure of 3,3,6,6-tetramethylmorpholine-2,5-dione, and its 5-monothioxo and 2,5-dithioxo derivatives
Mawad, Nasser,Ghorbani-Salman Pour, Fatemeh,Linden, Anthony,Heimgartner, Heinz
experimental part, p. 2326 - 2346 (2011/02/18)
The synthesis of 3,3-dimethylmorpholine-2,5-diones 4a was achieved conveniently via the 'direct amide cyclization' of the linear precursors of type 3, which were prepared by coupling of 2,2-dimethyl-2H-azirin-3-amines 2 with 2-hydroxyalkanoic acids 1. Thionation of 4a with Lawesson's reagent yielded the corresponding 5-thioxomorpholin-2-ones 10 and morpholine-2,5-dithiones 11, respectively, depending on the reaction conditions. The structures of 3aa, 4aa, 10a, and 11a were established by X-ray crystallography. All attempts to prepare S-containing morpholine-2,5-dione analogs or thiomorpholine-2,5-diones by cyclization of corresponding S-containing precursors were unsuccessful and led to various other products. The structures of some of them have also been established by X-ray crystallography.
3-(Dimethylamino)-2,2-dimethyl-2H-azirine as an α-Aminoisobutyric-Acid (Aib) Equivalent: Cyclic Depsipeptides via Direct Amide Cyclization
Obrecht, Daniel,Heimgartner, Heinz
, p. 329 - 338 (2007/10/02)
In MeCN at room temperature, 3-(dimethylamino)-2,2-dimethyl-2H-azirine (1) and α-hydroxycarboxylic acids react to give diamides of type 8.Selective cleavage of the terminal N,N-dimethylcarboxamide group in MeCN/H2O leads to the corresponding carboxylic acids 13.In toluene/PhSH, phenyl thioesters of type 11 are formed.Starting with diamides 8, the formation of morpholin-2,5-diones 10 has been achieved either by direct amide cyclization via intermediate 1,3-oxazol-5(4H)-ones 9 or via base-catalyzed cyclization of the phenyl thioesters 11.Reaction of carboxylic acids with 1, followed by selective amide hydrolysis, has been used for the construction of peptides from α-hydroxy carboxylic acids and repetitive α-aminoisobutyric-acid (Aib) units.Cyclization of 14a, 17a, and 20a with HCl in toluene at 100 deg C gave the 9-, 12-, and 15-membered cyclic depsipeptides 15, 18, and 21, respectively.
3-DIMETHYLAMINO-2,2-DIMETHYL-2H-AZIRIN ALS Aib-AEQUIVALENT BEI HETEROCYCLENSYNTHESEN; SYNTHESE VON 6-, 9-, 12- UND 15-GLIEDRIGEN RINGEN
Obrecht, Daniel,Heimgartner, Heinz
, p. 1921 - 1924 (2007/10/02)
The cyclization reaction of the dimethylamides 2b, 5, 6 and 7, resulting from the reaction of mandelic acid with the aminoazirine 1, yields the 6-, 9-, 12- and 15-membered cyclic depsipeptides 10 - 13, respectively.
