A rapid and facile synthesis of benzannulated 6,5-spiroketals from vinyl 1,1-diacylcyclopropanes is reported. The method utilizes mild reaction conditions with good to excellent yields and high diastereoselectivity. This methodology was then used to construct the core of berkelic acid.
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J Org Chem
December 2024
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
Drastic changes to the character of the acidic catalyst enable the reversal of the double alkyne benzannulation reaction output. In the presence of a strong Brønsted acid, 1,4-dihydropyrrolopyrroles undergo transformation which results in the formation of two 7-membered rings. Computational studies imply that the thermodynamically unfavored 7-membered ring is forged via the kinetically favored attack of a protonated alkyne at the position 3a of pyrrolopyrrole followed by a 1,2-vinyl shift.
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Chemistry
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Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada.
Ligands containing phenanthridine (benzo[c]quinoline) have presented notable exceptions to the conventional logic that increasing ligand benzannulation leads to bathochromic (red) shifts in the absorption and emission of their coordination complexes. The counterintuitive blue shifts have been attributed to the peculiar structure of phenanthridines, whose ground states are dominated by imine-bridged biphenyl resonance contributors. These serve to isolate the C=N unit electronically from the rest of the ligand framework and allow the C=N moiety to act as a 'shock-absorber', buffering against larger molecular distortions in a molecule's excited state, and reducing the observed pseudo-Stokes' shift.
View Article and Find Full Text PDFRecent advances in the transformation of maleimides annulation.
Org Biomol Chem
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School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Republic of Korea.
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Fluoro-Agro chemicals Division, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India.
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Org Lett
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School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458, P. R. China.
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