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We have developed an efficient synthetic strategy to assemble C3-symmetric molecules containing propellane moieties as end groups and a benzene ring as a central core. The synthesis of these C3-symmetric molecules involves simple starting materials. Our approach to C3-symmetric compounds relies on a Diels–Alder reaction, cyclotrimerization and ring-closing metathesis as key steps.

We report an efficient synthetic strategy to diverse hydantoins and thiohydantoins involving a three-component reaction with the aid of deep eutectic solvent. Here, N,N'-dimethyl urea and N,N'-dimethyl thiourea play a dual role as reactant and reaction medium along with l-(+)-tartaric acid. The three-component reaction provides an easy access to 5-amino-1,3-dialkyl-substituted hydantoins and thiohydantoins in good yields.

A concise and simple synthetic approach to cis-syn-cis-triquinanes and -propellanes has been demonstrated via olefin metathesis starting with exo-nadic anhydride. This approach involves a ring-opening and ring-closing metathesis sequence of norbornene derivatives using Grubb's catalyst. Early-stage diallylation of norbornene derivatives is demonstrated followed by ring-closing metathesis that delivers propellanes exclusively. Surprisingly, ring-opening metathesis, late-stage diallylation, followed by ring-closing metathesis delivers triquinane as well as propellane derivatives.

We report a simple, one-pot, and metal free benzannulation protocol to carbazoles starting with indoles, carbonyl compounds and an appropriate dienophiles. Mechanistically, this strategy generates an in situ diene by condensation between indole and carbonyl compound succeed and subsequent dehydration. Later, Diels–Alder reaction of this diene with a suitable dienophile followed by oxidation delivers the carbazole derivative. This methodology provide an easy access to carbazoles containing 1,4-naphthoquinone moiety.

In this report, we compiled various strategies involving a ring-rearrangement metathesis as a key step to assemble diverse molecules. Popular name reactions such as Grignard reaction, Overman rearrangement, Fischer indolization, Beckmann rearrangement and Diels–Alder reaction were used in combination with ring-rearrangement metathesis to construct complex targets. Additionally, C H activation and RRM strategy has been used to assemble azacycles. In some instances, the ring-rearrangement metathesis was expected to occur; however, ring-opening metathesis products were realized. These methods were included in the miscellaneous section. We anticipate that the lessons learned here are useful in designing complex polycyclic and heterocyclic targets suitable for biological and material science applications. Beside our work, we have also included others work as a background information.

Simple synthetic approaches to pyridocarbazole and azepinocarbazole derivatives have been reported via Fischer indolization, Grignard reaction and olefin metathesis as key steps. In addition, a combination Sonogashira coupling and Pauson-Khand reaction has been used to assemble extended pyridocarbazole derivative. (C) 2017 Elsevier Ltd. All rights reserved.

New synthetic strategies to indolocarbazoles have been reported via two-fold Fischer indolization under green conditions using L-(+)-tartaric acid and N,N-dimethyl urea. Starting with cyclohexanone, a bench-top starting material, this methodology has been extended to the total synthesis of natural products such as tjipanazoles D and I as well as the core structure of asteropusazole and racemosin B. Here, atom economical reactions like ring-closing metathesis, enyne-metathesis, and the Diels–Alder reaction have been used as key steps. Diverse strategies demonstrated here are useful in medicinal chemistry and materials science to design a library of decorated indoles.

A concise and simple synthetic approach to cis-syn-cis-triquinanes and -propellanes has been demonstrated via olefin metathesis starting with exo-nadic anhydride. This approach involves a ring-opening and ring-closing metathesis sequence of norbornene derivatives using Grubb’s catalyst. Early-stage diallylation of norbornene derivatives is demonstrated followed by ring-closing metathesis that delivers propellanes exclusively. Surprisingly, ring-opening metathesis, late-stage diallylation, followed by ring-closing metathesis delivers triquinane as well as propellane derivatives.

A new route has been reported for the synthesis of densely oxygenated polycyclic aromatic compounds via cycloaddition approach. This strategy involves the Dotz benzannulation and Diels-Alder reaction as key steps. Naphthalene synthons required here were generated by Dotz benzannulation between aryl chromium carbene complexes and symmetrical internal alkyne. (C) 2016 Elsevier Ltd. All rights reserved.