Analysis of the mechanism for Rh-mediated C-H amination has led to the development of a remarkably effective dinuclear Rh catalyst derived from 1,3-benzenedipropionic acid. This unique complex, Rh2(esp)2, is capable of promoting both intra- and intermolecular C-H oxidation reactions, and in all cases is superior to Rh2(O2CtBu)4. For the first time, C-H insertion is described with urea and sulfamide substrates to give 1,2- and 1,3-diamine derivatives, respectively. In addition, intermolecular amination of benzylic and secondary C-H bonds is shown to proceed efficiently even under conditions in which the starting alkane is employed as the limiting reagent.
A grand opening: N-Boc-N-alkylsulfamides are effective substrates for the title transformation. Oxidative cyclization is highly chemoselective as well as being both stereospecific and diastereoselective. With the advent of new protocols that facilitate ring opening of the six-membered-ring heterocyclic products, access to differentially protected 1,3-diamines has been made possible (see scheme).
Schließen und öffnen: N‐Boc‐N‐alkylsulfamide sind geeignete Substrate für die Titelreaktion. Die oxidative Cyclisierung im ersten Schritt ist hoch chemoselektiv sowie stereospezifisch und diastereoselektiv. Mit neuen Verfahren zur Öffnung der dabei erhaltenen Sechsringheterocyclen werden unterschiedlich geschützte 1,3‐Diamine zugänglich (siehe Schema).magnified image
The title reaction affords a variety of imidazolidin-2-ones and 2-aminoimidazolines in high yields using Rh2(esp)2 as the catalyst. The protecting group can easily be removed with Zn/AcOH. The products are useful intermediates for the preparation of natural compounds. -(KIM, M.; MULCAHY, J. V.; ESPINO, C. G.; DU BOIS*, J.; Org. Lett. 8 (2006) 6, 1073-1076; Dep. Chem., Stanford Univ., Stanford, CA 94305, USA; Eng.) -R. Steudel 30-128
Thiadiazine derivatives R 0660Synthesis of 1,3-Diamines Through Rhodium-Catalyzed C-H Insertion. -A variety of N-Boc-N-alkylsulfamides can be used as effective substrates for the title reaction. The oxidative cyclization is highly chemoselective as well as stereospecific and diastereoselective. Two complementary ring opening methods for the thiadiazine products give access to differently protected diamines. -(KUROKAWA, T.; KIM, M.; DU BOIS*, J.; Angew. Chem., Int. Ed. 48 (2009) 15, 2777-2779; Dep. Chem., Stanford Univ., Stanford, CA 94305, USA; Eng.) -Klein 30-174
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