<i>anti</i>-Tricyclo[4.2.1.1<sup>2,5</sup>]deca-3,7-diene-9,10-dione

Gidaly, Matthew P.; Harris, Andria D.; Amado-Sierra, Maria del Rosario I.; Jones, Daniel S.; Etzkorn, Markus

doi:10.1107/s1600536809005844

Cited by 3 publications

(1 citation statement)

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“…By spectroscopy, the structure of 5j , 5k , and 5l could not be determined unambiguously, although mass spectrometry indicated a “dimeric compound”, formally arising from two molecules of 3j – 3l and elimination of two molecules of water. An unequivocal structural elucidation was possible by an X‐ray analysis of compound 5j (Figure ), showing that a compound with a C 2 ‐symmetric anti ‐tricyclo[4.2.1.1 2,5 ]deca‐3,7‐diene‐9,10‐dione core was formed . Due to the high similarity of the NMR data of 5j with those of 5k and 5l we can assume that the latter show the same connectivity of atoms.…”

Section: Resultsmentioning

confidence: 95%

Alkoxyallene‐Based LANCA Three‐Component Synthesis of 1,2‐Diketones, Quinoxalines, and Unique Isoindenone Dimers and a Computational Study of the Isoindenone Dimerization

et al. 2020

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A series of β‐alkoxy‐β‐ketoenamides was prepared by the well‐established LANCA three‐component reaction of lithiated 1‐(2‐trimethylsilylethoxy)‐substituted allenes, nitriles, and α,β‐unsaturated carboxylic acids. The α‐tert‐butyl‐substituted compounds were smoothly converted into the expected 1,2‐diketones by treatment with trifluoroacetic acid. A subsequent condensation of the 1,2‐diketones with o‐phenylenediamine provided the desired highly substituted quinoxalines in good overall yield. Surprisingly, the α‐phenyl‐substituted β‐alkoxy‐β‐ketoenamides investigated afford not only the expected 1,2‐diketones, but also pentacyclic compounds with an anti‐tricyclo[4.2.1.12,5]deca‐3,7‐diene‐9,10‐dione core. These interesting products are very likely the result of an isoindenone dimerization which was mechanistically studied with the support of DFT calculations. Under the strongly acidic reaction conditions, a stepwise reaction is likely leading to a protonated isoindenone as reactive intermediate. It may first form a van der Waals complex with a neutral isoindenone before the two regio‐ and diastereoselective ring forming steps occur. Interestingly, two neutral or two protonated isoindenones are also predicted to dimerize giving the observed pentacyclic product.||||||

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Section: Resultsmentioning

confidence: 95%