Regioselective Metallative Functionalization of 5-Azaindole

Significance

The C-2- and C-3-controlled functionalization of 5-azaindoles using directed ortho-metallation (DoM) and metal-halogen exchange processes is reported. The choice of the directed metallation group (DMG) and the lithium base source were found to be crucial for the achievement of the observed results. Thus, using the N-benzenesulfonyl DMG allowed C-2 deprotonation with LDA and thereby the synthesis of various corresponding products such as halo derivatives, stannanes and boronic esters in good to excellent yields. On the other hand, electrophilic iodination followed by lithium-halogen exchange and electrophile quench led to similarly diverse C-3-substituted products in reasonable to excellent yields.