Selective Synthesis of Six Products from a Single Indolyl α‐Diazocarbonyl Precursor

Abstract

Indolyl α-diazocarbonyls can be selectively cyclized to give six distinct products through the careful choice of catalyst and reaction conditions. A range of catalysts were used, including complexes of Rh(II) , Pd(II) , and Cu(II) , as well as SiO2 , to promote diazo decomposition and subsequent cyclization/rearrangement through a range of mechanistic pathways.

Selectivity, Speciation, and Substrate Control in the Gold-Catalyzed Coupling of Indoles and Alkynes

“…In all cases the calculated transition states for carbon–carbon bond formation are located at low energy (<41 kJ mol –1 with respect to the reference state) and the C–C bond formation ( 1 → 2 ) step was calculated to be almost barrierless. These results, and others, 10 − 17 demonstrate the synthetic versatility of 1 as a framework to access a range of important structural motifs.…”

Selective Synthesis of Six Products from a Single Indolyl α‐Diazocarbonyl Precursor

“…Communications product 4a was much more surprising,w ith the structure of this product confirmed by X-ray crystallography. [14] It was found that the selective synthesis of either product could be achieved, with the reaction outcome being dependent on the presence of air in the reaction. By switching the reaction solvent from CH 2 Cl 2 to chloroform, reducing catalyst loading to 5mol %, and performing the reaction under oxygen-free conditions, 3a was isolated in 92 %y ield (Scheme 1).…”

“…Both product structures were confirmed by X-ray analysis. [14] Next, the palladium(II)-and copper(II)-catalyzed reactions were optimized, thus allowing selective formation of the C2-annulated product 5aand carbazole 6ausing Pd(MeCN) 4 -(BF 4 ) 2 (5 mol %) and Cu(OTf) 2 (20 mol %), respectively (Scheme 4). [18,19] Ak ey difference between these reactions is that it is necessary to perform the carbazole-forming reaction under oxygen at 50 8 8C.…”

Synthesis of Structurally Diverse N‐Substituted Quaternary‐Carbon‐Containing Small Molecules from α,α‐Disubstituted Propargyl Amino Esters

“…[23] Moreover,w ithin af ragment-based drug discovery context,t here have been recent calls for the design and synthesis of novel compounds that feature multiple 3D growth vectors whilst incorporating polar functionality form olecular recognition. [24] In response to this, notable examples of efficient syntheses of diverse sp 3 -rich libraries have been recently published, [25][26][27][28][29][30][31][32] however there is stilla no utstanding need for diversel ibraries featuring this key N-containing quaternary stereocenter motif.…”