The development of efficient synthesis of structurally complex heterocycles emerges as an important agenda owing to their utility in many areas including medicine and materials. This talk will describe our recent efforts toward method development for construction of various heterocyclic scaffolds.[1,2] 1) Tandem cross-dehydrogenative cross coupling followed by intramolecular annulation. 2) Divergent reactivity of a-imino carbenes toward unreactive nucleophiles for heterocycle synthesis. In the first part, an efficient synthesis of indolopyrans and pyrrolopyrans based on tandem cross-dehydrogenative coupling followed by annulation will be presented. Cross-dehydrogenative coupling reaction offers broad advantages including obviating prefunctionalization of coupling partners and environmentally friendly conditions. Substantial increase in molecular complexity can be further achieved by combination with subsequent transformations in a tandem fashion. As such, tandem cross-dehydrogenative coupling followed by intramolecular annulation is deemed as a powerful approach to build molecular complexity for heterocyclic scaffolds. Nevertheless, the design of substrates and compatibility of reaction conditions pose significant challenges in the development of tandem reactions. Iodine-mediated reactions have drawn a renewed attention due to its versatile reactivity, benign environmental impact, and more economical processes. Furthermore, the demands for transition metal-free reactions from the pharmaceutical industry calls for the development of alternative reaction conditions. The synthetic method presented today allows the formation of highly substituted indole- and pyrrole-fused pyrans. Examination of substrates with various functionalities has been performed to establish the efficiency and selectivity of the reaction. In order to shed light on the reaction mechanism, several reactions designed to identify putative reactive species and intermediates have been performed. The second part will describe our efforts to identify catalysts that form a-imino carbene-metal complexes with enhanced reactivity leading to the coupling of weak nucleophiles including enol ethers and nitriles. The diverse reactivity of the carbene complexes allowed us to develop highly efficient synthesis of pyrroles and oxazoles from common substrates depending on coupling partners.