@article {49024,
	title = {Bronsted acid-promoted cyclodimerization of α,β-unsaturated γ-ketoesters: construction of fused pyrano-ketal-lactones and γ-ylidene-butenolides},
	journal = {ACS Omega},
	volume = {9},
	year = {2024},
	month = {APR },
	pages = {19859-19878},
	type = {Article},
	abstract = {<p>
	Unprecedented MsOH-promoted diastereoselective cascade dimerization and intramolecular lactonization of readily accessible alpha,beta-unsaturated gamma-ketoesters are presented. The results obtained in this work, control experiments, and density functional theory (DFT) calculations suggested that the initial enolization and E to Z isomerization/equilibration of olefin (C=C) of substrate alpha,beta-unsaturated gamma-ketoesters give a Z-isomer preferentially over an E-isomer. Subsequently, the Z-isomer undergoes intermolecular annulation with alpha,beta-unsaturated gamma-ketoesters via domino Michael addition/ketalization/lactonization steps to furnish fused tetracyclic pyrano-ketal-lactone. However, the Z-isomer prefers intramolecular trans-esterification in a competing pathway and gives bicyclic gamma-ylidene-butenolide. The key features of this work include simple Br \&amp; oslash;nsted acid catalysis, the formation of three bonds, two rings, and three contiguous stereogenic centers in a single step, DFT calculations, and the assignment of relative stereochemistry through X-ray diffraction (XRD) and two-dimensional (2D) nuclear magnetic resonance (NMR) analyses.</p>
},
	issn = {2470-1343},
	doi = {10.1021/acsomega.3c08873},
	author = {Vinodkumar, Ramavath and Nakate, Ashwini K. and Sharma, Himanshu and Vanka, Kumar and Rama Krishna, Gamidi and Kontham, Ravindar}
}
@article {49092,
	title = {Br{\o}nsted acid- and Ni(<sc>ii</sc>)-catalyzed C-H oxidation/rearrangement of cyclotriveratrylenes (CTVs) to cyclic and acyclic quinones as potential anti-cancer agents},
	journal = {Organic and biomolecular chemistry},
	volume = {22},
	year = {2024},
	month = {JAN },
	pages = {1038-1046},
	type = {Article},
	abstract = {<p>
	This paper describes a simple and practical protocol for the direct synthesis of acyclic and cyclic quinone derivatives via an acid-promoted nickel(ii)-catalyzed inner rim C-H oxidation of cyclotriveratrylene (CTV) and its analogues. The cyclic quinone derivatives resulted from trimethoxy-cyclotriveratrylene (TCTV) through C-C bond formation via intramolecular ipso substitution followed by subsequent anionic rearrangement containing stereo-vicinal quaternary centers. The DFT calculations strongly support the experimental findings and reveal the role of Bronsted acids in the C-H bond activation of CTV. All the newly synthesized compounds were screened for their in vitro anti-cancer activity using colorimetric SRB assay analysis. Among them, compounds 3a, 3d, 3h, 4a, 4b, 4c and 4e exhibited moderate anticancer activity against A549, HCT-116, PC-3, MDA-MB-231, HEK-293 and SW620 human cancer cell lines.</p>
},
	issn = {1477-0520},
	doi = {10.1039/d3ob01428b},
	author = {Darole, Ratanamala S. and Choudhary, Shailendra Singh and Sharma, Himanshu and Mali, Bhupendra P. and Gopu, Booblan and Vanka, Kumar and Senthilkumar, Beeran}
}
