Target Specific Tactics in Olefin Metathesis: Synthetic Approach to cis-syn-cis-Triquinanes and -Propellanes

Abstract

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.

Synthesis and Structure Revision of Dichrocephones A and B

“…The configuration of the quaternary center was determined by VCD spectroscopy and is in agreement with Werner's proposal. The construction of the propellane core was completed by convex face 1,4‐addition of a mixed vinyl cuprate to give 11 in 97 % yield, followed by ring‐closing metathesis using 1 mol % of Umicore M71SIPr catalyst to afford propellenedione 6 .…”

Design and Synthesis of Polycycles, Heterocycles, and Macrocycles via Strategic Utilization of Ring‐Closing Metathesis

“…Recently, an efficient route towards the synthesis of various triquinanes and propellane derivatives was demonstrated via a RCM protocol . The required building block 182 was assembled from easily accessible exo compound 180 by employing thermal condensation with aniline 181 in Et 3 N. The compound 182 was then treated with allyl bromide ( 15 ) to give the required RCM precursor 183 .…”

Selectivity in Ring‐Closing Metathesis: Synthesis of Propellanes and Angular Aza‐tricycles

“…[3] Thereafter, one can assemble architecturally complex targets more easily with or without the involvement of protecting groups. [5] For example, synthesis of cis-syn-cis triquinane [6] over the propellanes, [7] tandem ring-closing metathesis (RCM) [8] followed by aromatization, chemo-selective self-metathesis [9] and crossmetathesis (CM) reactions. [5] For example, synthesis of cis-syn-cis triquinane [6] over the propellanes, [7] tandem ring-closing metathesis (RCM) [8] followed by aromatization, chemo-selective self-metathesis [9] and crossmetathesis (CM) reactions.…”

“…[4] Metathesis catalysts are found to be selective in many synthetic transformations. [5] For example, synthesis of cis-syn-cis triquinane [6] over the propellanes, [7] tandem ring-closing metathesis (RCM) [8] followed by aromatization, chemo-selective self-metathesis [9] and crossmetathesis (CM) reactions. [2a,4b,10] In this context, we have explored a new synthetic strategy to assemble propellanes in preference to the angular aza-tricyclic compounds using commercially available ruthenium carbene catalysts.…”