Enantioselective Total Synthesis of (+)-Lysergol: A Formal anti-Carbopalladation/Heck Cascade as the Key Step.

The enantioselective synthesis of (+)-lysergol was completed in 12 steps and an overall yield of 13% starting from a known literature precursor. The key step relies on a domino reaction containing a formal anti-carbopalladation, which is terminated by a β-silyl-directed Heck reaction. During this transformation, the two six-membered rings of the ergot scaffold are formed in a completely stereospecific manner.

Intramolecular trans-Dicarbofunctionalization of Alkynes by a Formal anti-Carbopalladation/Stille Cascade.

An intramolecular Pd-catalyzed trans-dicarbofunctionalization of internal alkynes using aryl bromides and aryl stannanes is presented. Tetrasubstituted double bonds embedded in an oligocyclic ring system are obtained in a regio- and diastereoselective fashion. The transformation features a broad substrate scope and functional-group tolerance.

Oligoene-Based π-Helicenes or Dispiranes? Winding up Oligoyne Chains by a Multiple Carbopalladation/Stille/(Electrocyclization) Cascade.

A domino approach consisting of up to five consecutive steps to access either highly substituted dispiranes or π-helicenes from oligoyne chains is reported. The domino sequence consists of several carbopalladation reactions, a Stille cross-coupling to obtain the helicenes, and, depending on the steric demands of the helicene, a final 6π-electrocyclization to afford the dispiranes. Formally, the latter transformation contravenes the Woodward-Hoffmann rules, as revealed by X-ray crystallography of the dispirane.

Intramolecular Formal anti-Carbopalladation/Heck Reaction: Facile Domino Access to Carbo- and Heterooligocyclic Dienes.

An intramolecular domino process consisting of a formal anti-carbopalladation followed by Heck reaction is realized. Complex oligo(hetero)cyclic scaffolds are efficiently obtained in one synthetic step from easily obtainable enyne precursors. In contrast to common syn-carbopalladation reactions of alkyne units, the carbopalladation employed here is designed to afford an anti-arrangement of the two new substituents across the emerging double bond.

π-Helicenes truncated to a minimum: access through a domino approach involving multiple carbopalladations and a Stille coupling.

A novel type of π-helicenes is reported, in which the π-system is truncated to an all-s-cis all-Z oligoene chain. A domino sequence was developed, consisting of up to four consecutive carbopalladation reactions and a terminal Stille cross-coupling, to generate these entities in one step from the respective linear oligoynes. Despite the minimal π-system, very high optical rotation values were encountered for the single enantiomers.

Dinitrogen splitting and functionalization in the coordination sphere of rhenium.

[ReCl3(PPh3)2(NCMe)] reacts with pincer ligand HN(CH2CH2PtBu2)2 (HPNP) to five coordinate rhenium(III) complex [ReCl2(PNP)]. This compound cleaves N2 upon reduction to give rhenium(V) nitride [Re(N)Cl(PNP)], as the first example in the coordination sphere of Re. Functionalization of the nitride ligand derived from N2 is demonstrated by selective C-N bond formation with MeOTf.