77298-07-8Relevant academic research and scientific papers
Cycloaddition Reactions of Heterocumulenes, XXIX. - Reactions of Thioketenes with Isocyanates
Schaumann, Ernst,Moeller, Marianne,Adiwidjaja, Gunadi
, p. 689 - 700 (2007/10/02)
The cycloaddition of thioketenes 1a-f to isocyanates 2a-f yields 4-thioxo-2-azetidinones 3 as main products, which may isomerize to 4-imino-2-thietanones 5.In competing reactions, 2,4-azetidinediones 8, N-sulfonylamides 9, and 3H-1,2,4-dithiazoles 15 are formed.Thioketenes 1 react with chlorosulfonyl isocyanate (20b) to give N-unsubstituted 4-thioxo-2-azetidinones 22.Depending on the thioketene 1 and the reaction conditions, compounds 23-26 also result.The consitutions of 15b and 23a were determined by X-ray structural analyses.
On the Reactivity of 4-Thioxo-2-azetidinones
Schaumann, Ernst,Moeller, Marianne
, p. 701 - 708 (2007/10/02)
Base-catalyzed alcoholysis of the N-S bond in N-sulfonyl-thioxoazetidinones 1 is a ready process; the resulting sulfonate then alkylates the liberated 2-.Alkylations of 2 under various conditions demonstrate that charge and thermodynamic control favor attack on nitrogen to give 5 rather than reaction on sulfur to give 4.Besides simple alkyl residues (4a-c, 5a-c) also fuctionalized alkyl (4d, e, g, m, n, o, 5d, e, g, i, m-o), aryl (5p), and acyl groups (5q) can be introduced and addition reactions (5r, s) achieved.Complex hydrides reduce the carbonyl group in 1, 5 to yield 8-10, but the C=N+ unit in the salt 6a to furnish β-lactam 11.Annulation of a five-membered ring to give 12 is achieved by 1,3-dipolar cycloaddition of dimethyl fumarate to in-situ generated azomethine ylide 6d.
4-thioxo-2-azetidinones by cycloaddition of thioketenes with isocyanates
Schaumann, Ernst,Roehr, Armin,Adiwidjaja, Gunadi
, p. 4247 - 4250 (2007/10/02)
The (2+2) cycloaddition of thioketenes 1 with isocyanates 2 yields 4-thioxo-2-azetidinones 3, which can be hydrolyzed to the N-unsubstituted compound 4 and thus used as versatile intermediates.
