first example of transition-metal-catalyzed C–H activations of 2-phenylisatogens with alkynes and sulfonyl azides has been developed using N-oxide as the directing group. Ru(II)-Catalyzed C–H alkenylation/cyclization and Ir(III)-catalyzed direct C–H sulfamidation proceeded with good yields and excellent functional group tolerance. Importantly, these two transformations provided straightforward routes
Ru-Catalyzed Redox-Neutral Cleavage of the N–O Bond in Isoxazolidines: Isatogens to Pseudoindoxyls via a One-Pot [3 + 2]-Cycloaddition/N–O Cleavage
作者:Chepuri V. Suneel Kumar、Chepuri V. Ramana
DOI:10.1021/acs.orglett.5b00837
日期:2015.6.19
A novel metal-catalyzed oxygen atom transfer reaction onto olefins is reported. By taking isatogens as substrates, a one-pot [3 + 2]-cycloaddition of nitrone with olefins followed by the Ru-catalyzed redox-neutral N-O bond cleavage of intermediate isoxazolidine has been executed as a simple method for the synthesis of 2,2-disubstituted pseudoindoxyls.
Rh(III)-Catalyzed C7-Alkylation of Isatogens with Malonic Acid Diazoesters
Rh(III)-catalyzed C7-alkylation of isatogens (indolin-3-one N-oxides) with malonicacid diazoesters has been developed. This strategy utilizes oxygen anion on the N-oxide group of isatogens as a directing group and successfully achieves the synthesis of a series of C7-alkylated isatogens with moderate to good yields (48–86% yields). Moreover, the N-oxides of isatogens can not only serve as the simple
Isatogenols as Precursors for the Synthesis of Fully Substituted Indolines through Regio- and Stereoselective [3 + 2] Cycloaddition Using Various Olefins
isatogen derivatives bearing a hydroxy group at the C3-position (isatogenol) and their synthetic application to highly regio- and stereoselective [3 + 2] cycloaddition reactions. This method provides facile access to polyfused and highly functionalized heterocycles including consecutive stereocenters. Furthermore, DFT calculations revealed that hydrogen bonding is a key to controlling the regio- and stereoselectivity