Substituents Regulate the Cyclization of Conjugated Alkynes to Accurately Construct Cyclo-(E)-[3]dendralenes

Substituent-regulated cyclization of conjugated alkynes with acid catalysis was developed in this paper, and it provides a straightforward synthesis of cyclic-(E)-[3]dendralenes. Depending on the electronic effect of the aromatic ring pairing, a variety of phosphinyl quintuplet/hexa cyclo-[3]dendralenes with diverse substitution patterns are accessible, with good efficiency and high stereoselectivity. This self-cyclization process achieves the first precise construction of a phosphinylcyclo-(E)-[3]dendralene from conjugated alkynes to aromatization.

[n]Dendralenes as a Platform for Selective Catalysis: Ligand-Controlled Cu-Catalyzed Chemo-, Regio-, and Enantioselective Borylations

We report the development of two complementary methods for the Cu-catalyzed anti-Markovnikov borylation of one specific olefin in 2-substituted [n]dendralenes (n = 3-6). The first protocol operates with a bisphosphine ligand and occurs with high regio- and chemoselectivity for the terminal double bond, independently of the number of cross-conjugated alkenes. We show that the use of a chiral phosphanamine ligand enables the highly chemo-, regio-, and enantioselective borylation of the alkene cross-conjugated with the terminal olefin in [n]dendralenes.

General Approaches to Structurally Diverse Isocyanoditerpenes

Since their discovery in the 1970s, the striking architectures and the unusual isonitrile functional groups of the isocyanoterpenes have attracted the interest of many organic chemists. The more recent revelation of their potent in vitro antiplasmodial activity sparked new endeavors to synthesize members of this family of secondary metabolites. In this Synopsis, we discuss three distinct strategies that each address multiple structurally different members of the isocyanoterpenes, ending with some of our group's recent contributions in this area.

Masked Ketenes as Dienophiles in the Diels–Alder Reaction

The Diels–Alder reaction is one of the most powerful, well-established, and versatile reactions in organic chemistry; however, its application in certain settings remains a challenge as a result of functional group incompatibility. In this review, we examine the methods in which masked ketenes can be employed as dienophiles, taking particular note of applications in complex settings.

Synthesis of highly functionalized [3]dendralenes and their Diels–Alder reactions displaying unexpected regioselectivity

Sequential olefinations were applied for the synthesis of acyclic tetrasubstituted [3]dendralenes, which did not cyclodimerize and displayed unusual regioselectivity in the Diels–Alder reaction.

Total synthesis of the pseudopterosin aglycones

The 15 published total syntheses of the pseudopterosins are reviewed, with focus on strategic considerations and an emphasis on ring formation.

Computational and synthetic studies with tetravinylethylenes

Computational and experimental studies offer fresh insights into the neglected tetravinylethylene class of compounds. Both the structures and the outcomes of exploratory reactions of the parent hydrocarbon are predicted and explained in detail through high-level composite ab initio MO G4(MP2) computational studies.

Tetravinylethylene

The first four-fold cross coupling reaction involving alkenic partners leads to the title hydrocarbon on multi-gram scale in one step from commercially available precursors. In stark contrast to its close structural relatives, tetravinylethylene is a remarkably robust, bench-stable compound. The π-bond rich hydrocarbon is shown to undergo one-pot sequences of pericyclic reactions leading to the formation of complex systems with four new rings, seven C-C bonds and ten stereocenters with a very high level of stereoselectivity. Insights into the reactivity of this and related systems is provided using the accurate composite ab initio MO G4(MP2) method.

Furanodendralenes

An examination of Diels-Alder reactions of furan-containing analogues of dendralenes has revealed complex and fascinating reaction sequences, which chart the inherent site and stereoselectivity of these processes and give rapid access to structures of high molecular complexity.

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

In the last few years, multicomponent reactions involving boron substituted 1,3-dienes have emerged as important tools in synthetic organic chemistry. The most significant recent results and developments obtained in this area are reported in this review.