Palladium-Catalyzed [2+3] Cycloaddition/Cross-Coupling Reaction: Z/E and Diastereoselective Synthesis of Dendralene-Functionalized Dihydrofurans

Hydroxyl-Directed Ru(II)-Catalyzed Synthesis of Fused Dihydrofurans Using 1,4-Dioxane and Sulfoxonium Ylides as Annulating Agents

An unprecedented annulation reaction is developed for the synthesis of dihydrofuran-fused compounds. In this Ru-catalyzed hydroxyl-group-directed reaction, easily affordable sulfoxonium ylides and 1,4-dioxane were used as the annulating partners. This is the first example of the use of 1,4-dioxane as a methylene source to construct a heterocyclic scaffold. A wide range of dihydrofuran0fused coumarins and naphthalenes were synthesized using this three-component reaction.

A General Stereoselective Synthesis of [4]Dendralenes

The first general synthesis of branched tetraenes ([4]dendralenes) involves two or three steps from inexpensive, commodity chemicals. It involves an unprecedented variation on Suzuki-Miyaura cross-coupling, generating two new C-C bonds in a one-flask operation with control of diastereoselectivity. The broad scope of the method is established through the synthesis of more than 60 diversely substituted [4]dendralene molecules, along with substituted buta-1,3-dienes and other [n]dendralenes. [4]Dendralenes are demonstrated to be significantly more kinetically stable than their well-known [3]dendralene counterparts. The first stereoselective synthesis of these compounds is also reported, through the catalyst-controlled generation of both E- and Z-diastereomeric products from the same precursor. Novel, through-conjugated/cross-conjugated hybrid molecules are introduced. The first selective dienophile cycloadditions to substituted [4]dendralenes are reported, thus paving the way for applications in target-oriented synthesis.