A new protocol for benzoannulation by double Claisen rearrangement and ring-closing metathesis reactions as key steps

A new methodology for benzoannulation has been developed by using double Claisen rearrangement followed by a one-pot ring-closing metathesis and DDQ oxidation sequence.© Elsevie

Metathesis of a novel dienediyne system: a unique example involving the usage of in situ generated ethylene as cross-enyne metathesis partner

A unique example of sequential ring-closing metathesis and cross-enyne metathesis is reported. Here, the in situ generated ethylene by product from ring-closing metathesis is trapped by alkyne moiety. No metathesis product formation was observed with more reactive second generation catalyst in the absence of ethylene. Differential chemoselectivity with the first and second generation Grubbs’ catalyst has been observed when the reaction was performed in presence of the external source of ethylene.© Elsevie

A retrospective on the design and synthesis of novel molecules through a strategic consideration of metathesis and Suzuki-Miyaura cross-coupling

Synergy in synthesis: Strategic consideration of metathesis and Suzuki-Miyaura (SM) cross-coupling for C-C bond-formation processes has opened up new and "green" synthetic routes to various complex targets. The use of this synergistic combination for the synthesis of supramolecular ligands, polyaromatic compounds, and complex natural products is covered in this Focus Review. In recent years, ruthenium-catalyzed metathesis and palladium-catalyzed Suzuki-Miyaura cross-coupling reactions have proven to be the most efficient tools for carbon-carbon bond formation in synthetic organic chemistry. This is mainly because of the stability and remarkable functional-group tolerance of these catalysts. Therefore, the strategic consideration of these two powerful reactions can eventually minimize the synthetic steps for the construction of complex target molecules. In this perspective we summarize the efforts of many research groups who have used the combination of these two powerful reactions (either together in concert or separated by a few multistep sequences) for the synthesis of supramolecular ligands, polyaromatic compounds, and complex natural products

Metathetic approach to naphthoxepin and spirocyclic molecular frameworks

An efficient method for the synthesis of naphthoxepin and spirocyclic skeletons starting from β-naphthol has been developed. The Claisen rearrangement and the ring-closing metathesis reaction are used as key steps for their assembly.© Elsevie

Suzuki-Miyaura cross-coupling and ring-closing metathesis: a strategic combination for the synthesis of cyclophane derivatives

The synthesis of cyclophane derivatives through a sequence involving Suzuki-Miyaura cross-coupling between α, α'-dibromo-m-xylene and arylboronic acid derivatives, alkenylation and ring-closing metathesis has been achieved. One of the cyclophanes was obtained by tandem isomerization and metathesis. Significant magnetic anisotropic effects on the intra-annular hydrogen atoms were observed

Understanding the role of intramolecular ion-pair interactions in conformational stability using an ab initio thermodynamic cycle

Intramolecular ion-pair interactions yield shape and functionality to many molecules. With proper orientation, these interactions overcome steric factors and are responsible for the compact structures of several peptides. In this study, we present a thermodynamic cycle based on isoelectronic and alchemical mutation to estimate intramolecular ion-pair interaction energy. We determine these energies for 26 benchmark molecules with common ion-pair combinations and compare them with results obtained using intramolecular symmetry-adapted perturbation theory. For systems with long linkers, the ion-pair energies evaluated using both approaches deviate by less than 2.5% in vacuum phase. The thermodynamic cycle based on density functional theory facilitates calculations of salt-bridge interactions in model tripeptides with continuum/microsolvation modeling, and four large peptides: 1EJG (crambin), 1BDK (bradykinin), 1L2Y (a mini-protein with a tryptophan cage), and 1SCO (a toxin from the scorpion venom).Comment: version 2, included basis set analysis (aug-cc-pVTZ vs jun-cc-pVDZ

Formation of arenes via diallylarenes: strategic utilization of Suzuki-Miyaura cross-coupling, claisen rearrangement and ring-closing metathesis

Two new synthetic strategies for benzoannulation are reported. The first strategy is based on the Suzuki-Miyaura cross-coupling reaction. To this end, various ortho-diallylbenzene derivatives were prepared from the corrresponding diiodo derivatives by an allylation strategy using an allylboronate as coupling partner. These diallyl derivatives were subjected to a ring-closing metathesis (RCM) and one-pot dichlorodicyanoquinone (DDQ) oxidation sequence to deliver 2-substituted naphthalenes. In the second strategy, a double Claisen rearrangement and RCM protocol have been used as key steps to give highly functionalized benzoannulated quinone derivatives

Diversity-oriented approach to biologically relevant molecular frameworks starting with β-naphthol and using the Claisen rearrangement and olefin metathesis as key steps

A diversity-oriented approach for the synthesis of various structurally different molecular frameworks from readily accessible and common precursors is described. A Claisen rearrangement followed by ring-closing metathesis or ethylene-promoted ring-closing enyne metathesis has been utilized as the key synthetic transformation to generate naphthoxepine derivatives. The ring-closing metathesis approach has also been used to generate spirocyclic compounds and the pleiadene framework

Synthesis of novel quinone-amino acid hybrids via cross-enyne metathesis and Diels-Alder reaction as key steps

A "Building Block Approach" for the synthesis of various quinone-amino acid hybrids through ethylene cross-enyne metathesis and Diels-Alder reaction as key steps is described. A library of comformationally constrained quinone-based phenylalanine derivatives and dicarba analogs of cystine have been generated starting from a common precursor using Grubbs' catalysts. This methodology has also been extended for the synthesis of fullerene-based dicarba analogs of cystine

New synthetic approach to a [1.1. 6] metapara cyclophane derivative via Suzuki-Miyaura cross-coupling and ring-closing metathesis

The synthesis of a [1.1.6] metapara cyclophane derivative, 1,5(1,4),3(1,3)-tribenzenacycloundecaphan-8-ene-6,11-dione, has been achieved via the Suzuki-Miyaura cross-coupling of α, α'-dibromo-m-xylene with an arylboronic acid derivative followed by an allylation and ring-closing metathesis reaction sequence