Synthesis and Rearrangement of Cage [4.3.2]Propellanes that Contain a Spiro Linkage

Abstract

Rearranged cage ketones 6a and 6b are reported in eight linear synthetic steps from 2,5‐dimethoxybenzaldehyde 9 without the use of protecting groups. In this regard, Diels–Alder reaction, [2+2]photocycloaddition and Lewis acid promoted rearrangement with BF3·OEt2 were used as key steps. Surprisingly, during the ring expansion process with Lewis acid, solvent incorporation occurred. This rearrangement approach has provided difficult complex targets through non‐obvious synthetic routes. The rearrangement process demonstrated here opens up a new synthetic strategy to interesting and unusual cage molecules.

Pentacycloundecane (PCUD)‐Based Cage Frameworks as Potential Energetic Materials: Syntheses and Characterization

“…Recently, some efforts have been directed in developing new strategies to design various interesting and unusual polycyclic cage compounds via RCM and rearrangement approaches [67–70] . The present work is aimed at gaining a detailed insight into the chemistry of PCUD‐derived energetic cage compounds along with their synthetic protocols.…”

“…[16] Recently, some efforts have been directed in developing new strategies to design various interesting and unusual polycyclic cage compounds via RCM and rearrangement approaches. [67][68][69][70] The present work is aimed at gaining a detailed insight into the chemistry of PCUD-derived energetic cage compounds along with their synthetic protocols. In continuation of an effort to expand the chemical space of cage compounds, our efforts have been diverted to study the energetic properties of high nitrogen cage frameworks using Diels-Alder (DA) chemistry [71] and [2 + 2] photocycloaddition [72] as the key steps.…”

Synthetic Approach to Oxacycles via the Application of Ring‐Rearrangement Metathesis

“…Our synthetic strategy starts with the preparation of DA adduct 2, involving the reaction between cyclopentadiene and pbenzoquinone derivative 1. [5,6] The norbornene derivative 2 underwent Grignard reaction to produce diallyl compound 3 which may be useful substrate for RRM. Unfortunately, the diallyl compound 3 decomposed during metathesis sequence (Scheme 1).…”

Hexacyclo[6.5.1.01,5.05,12.07,11.09,13]tetradecane-4,6,14-trione

“…The title compound (II) was synthesized (Fig. 2) from inexpensive and commercially available starting materials such as 2,5-dimethoxy benzaldehyde using the Diels-Alder reaction as a key step (Kotha et al, 2017).…”