New in situ trapping metalations of functionalized arenes and heteroarenes with TMPLi in the presence of ZnCl2 and other metal salts.

The addition of TMPLi to a mixture of an aromatic or heteroaromatic substrate with a metal salt such as MgCl2, ZnCl2, or CuCN at -78 °C first leads to lithiation of the arene followed by transmetalation with the metal salt to afford functionalized organometallic compounds of Mg, Zn, or Cu. This in situ trapping method allows an expedited metalation (-78 °C, 5 min) of a range of sensitive pyridines (bearing a nitro, ester, or cyano group) and allows the preparation of kinetic regioisomers of functionalized aromatic compounds or heterocycles not otherwise available by standard metalating agents, such as TMPMgCl⋅LiCl or TMPZnCl⋅LiCl.

Preparation and reactions of heteroarylmethylzinc reagents.

We report a general preparation of heteroarylmethylzinc chlorides by direct zinc insertion into heteroarylmethyl chlorides, along with a facile and straightforward synthesis of these heterocyclic chloromethyl precursors. We demonstrate that heteroarylmethylzinc reagents undergo various reactions including cross-couplings, allylations, acylations, and addition reactions to aldehydes, leading to polyfunctional heterocyclic products. Furthermore, these heteroaromatic zinc compounds prove to be versatile reagents for the preparation of various N- and O-heterocycles and give access to an analogue of a CB1 modifier.

Full functionalization of the 7-azaindole scaffold by selective metalation and sulfoxide/magnesium exchange.

Filling positions: 7-Azaindoles are important targets in the pharmaceutical industry. All five carbon positions of the azaindole ring system can be functionalized in a predictable manner starting from the appropriately substituted azaindole 1 by directed metalation and halogen/magnesium and sulfoxide/magnesium exchange. The products are fully substituted azaindoles of type 2.