Carbon dioxide as a carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas: Scope and limitations
Carbon dioxide can be used as a convenient carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas. The transient carbamate anion generated by treating a primary or secondary amine group in basic media can be activated with phosphorylating agents such as Diphenylphosphoryl azide (DPPA) and Diphenyl chlorophosphate (DPPCl) but also with other types of electrophiles such as SOCl2, TsCl, or AcCl. The intramolecular trapping of the activated carbamate by a hydroxyl group leads to the formation of 2-oxazolidinones or 2-oxazinones in good to excellent yields. This methodology was successfully applied to the synthesis of cyclic ureas up to 7-membered rings from the corresponding diamines.
Paz, Jairo,Perez-Balado, Carlos,Iglesias, Beatriz,Munoz, Luis
experimental part
p. 3037 - 3046
(2010/07/15)
Facile synthesis of β-amino disulfides, cystines, and their direct incorporation into peptides
Herein, we report a simple and efficient methodology for the synthesis of β-amino disulfides by regioselective ring opening of sulfamidates with benzyltriethylammonium tetrathiomolybdate [BnNEt3] 2MoS4. Stability and reactivity of different protecting groups under the reaction conditions have been discussed. This methodology has also been extended to serine and threonine derived sulfamidates to furnish cystine and 3,3′-dimethyl cystine derivatives. Georg Thieme Verlag.
Nasir Baig,Kanimozhi, Catherine K.,Sudhir, V. Sai,Chandrasekaran, Srinivasan
scheme or table
p. 1227 - 1232
(2009/09/06)
Asymmetric epoxidation of styrenes catalyzed by molybdenum complexes with amino alcohol ligands
Two common amino alcohols, prolinol and isolucinol, and their derivatives have been screened to coordinate with MoO2(acac)2 to form in situ catalysts for asymmetric epoxidation of styrenes with the highest enantioselectivity of 84% for 4-fluoro-styrene under the optimized reaction conditions.
Wang, Yi,Wu, Zhiqing,Li, Zhengkai,Zhou, Xiang-Ge
body text
p. 2509 - 2511
(2009/09/05)
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