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).

The total synthesis of (+)-duocarmycin A and SA through a common indoline intermediate is described. The key reactions include selective lithiation of a 2,6-dibromoiodobenzene derivative and diastereoselective addition to a chiral nitroalkene, copper-mediated aryl amination, and addition of aryllithium to azlactones.

A new method for introduction of indolylmethyl group to aldehydes or ketones using diethyl (o-isocyanophenylmethyl)phosphonate through Horner-Wadsworth-Emmons condensation, thiolmediated radical cyclization, and the subsequent desulfurization is described. The Horner-Wadsworth-Emmons reagent was prepared from 2-nitrobenzaldehyde in a concise three-step sequence.

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

An intramolecular thioester-olefin cross-coupling reaction for the preparation of cyclic ketone structures from unsaturated thioesters is described. This method capitalizes on the unique reactivity of thioesters with low-valent palladium catalysts and copper(I) salts to form acyl-metal species. Trapping of such intermediates with alkene functional groups generates the corresponding exo-methylene cycloalkanone products. Unsaturated thioester substrates, which can be accessed using a suite of modern synthetic methods, can now be regarded as precursors to complex carbocyclic derivatives. Fig. 1 A palladium-catalyzed thioester carbocylization reaction.