The catalytic C-H functionalisation of aromatic heterocycles is a powerful method in synthesis. Within this field, C-H borylation has proven a remarkably adept methodology. This reaction transforms a C-H bond into a C-B bond, allowing installation of boronic ester or boronic acid functional groups on heteroaromatic rings. This reaction creates a point for further synthetic derivatisation at a position originally devoid of functionality. In the past few years, we, and others, have introduced new catalytic approaches that expand this concept to metallic main group elements. Methods for the catalytic alumination (C-H to C-Al), magnesiation (C-H to C-Mg) and zincation (C-H to C-Zn) of aromatic and heteroaromatic ring systems have been reported. These approaches are complementary to C-H borylation, in that they create organometallic reagent in place of organoborane products. These species are expected to show enhanced reactivity, some interesting examples of which are emerging. For example, catalytic C-H alumination of benzofuran, furans, and dihydropyrans was found to occur exclusively in the 2-position using 1 as a reagent and [Pd(PCy3)2] as a catalyst. These 2-metallated heterocycles are only kinetic products as they converted to ring-expanded aluminacycle at longer reaction times (Figure ). To the best of our knowledge there is limited precedent for this type of reaction in C-H borylation methodology, although 2-borylated and 2-silylated furans have been shown to convert to ring expanded products under specialised conditions. The ring-expanded aluminacycles 3 are potentially useful synthetic intermediates.