Realization of Photo‐Thermal Metathesis Under Microwave Irradiation Conditions: An Entry to Triquinane Frameworks

Abstract

We report a simple and convenient synthetic route to cis,syn,cis triquinane frameworks under microwave irradiation conditions starting with cage diones. This is feasible because of the substituents present in the precursors, which facilitate the metathesis under milder reaction conditions as compared to normal flash vacuum pyrolysis conditions (6 00°C). Isomerization of the double bond was realized under microwave irradiation to deliver the other triquinanes, which are useful precursors for natural product synthesis.

Rational Design of Triplet Sensitizers for the Transfer of Excited State Photochemistry from UV to Visible

“…This interesting observation has not been previously reported in the literature, and close inspection of the UV–vis spectra of the pale yellow starting dione revealed a weak, but significant absorption tail overlapping with the output of the 455 nm COB. This move to the visible should prove to be a useful observation for a variety of Cookson’s dione type cycloadditions which have previously been thought to be restricted to the UV.…”

“…Excited state photochemistry 1 involves the formation of bonds by the reaction of molecules in an electronically excited state. Its purest embodiment occurs without catalysts or reagents by irradiation with UV light, most commonly in the region of 250−400 nm.…”

Synthetic Approaches to Natural and Unnatural Tetraquinanes

“…Recently, Kotha and co‐workers developed a convenient procedure to access spiro‐ tetracyclic system with cis‐syn‐cis angular triquinanes moiety (Scheme 15). To this end, the spiro cage dione 105 was subjected to microwave irradiation to deliver diallyl tetraquinanes 106 a and 106 b [9h] …”

rac-(2aS,2a1 R,3aR,3a1 S,5aS,6aR)-2a-Allyl-2,4-dichloro-2a,2a1,3a1,5a,6,6a-hexahydro-3aH-3-oxadicyclopenta[cd,gh]pentalen-3a-ol

“…Therefore, convenient methods to prepare and functionalize triquinanes and the study of their stereochemistry are useful exercises (Mehta & Rao, 1985). Our group has prepared triquinanes from cage compounds in a simplified manner using microwave irradiation (Kotha et al, 2019). Thereafter, we attempted to functionalize the triquinanes and observed a transannular attack at the keto centre (O1-C1-O2) leading to the formation of the title compound, 1.…”