@article {48160,
	title = {Ready access to benzannulated [5,5]-oxaspirolactones using Au(III)-catalyzed cascade cyclizations},
	journal = {Journal of Organic Chemistry},
	volume = {87},
	year = {2022},
	month = {MAR},
	pages = {3025-3041},
	type = {Article},
	abstract = {<p>
	This work showcases an unprecedented Au(III)-catalyzed cascade cyclization of 2-(4-hydroxyalkynyl)benzoates to access benzannulated [5,5]-oxaspirolactones related to biologically active natural products. This reaction proceeds through an initial 5-endo-dig mode of hydroalkoxylation of the alkynol segment to give the oxocarbenium species (via cyclic enol-ether) followed by the addition of carboxylate onto the oxocarbenium that delivers the oxaspirolactone scaffold. While testing this method{\textquoteright}s scope, we found that the steric and electronic environment of the hydroxyl group could alter the reaction pathway that delivers isochromenone through a competitive 6-endo-dig mode of attack of the carboxylate onto the tethered alkyne.</p>
},
	issn = {0022-3263},
	doi = {10.1021/acs.joc.1c02843},
	author = {Mankad, Yash and Thorat, Sagar S. and Das, Pronay and Krishna, Gamidi Rama and Kontham, Ravindar and Reddy, D. Srinivasa}
}
@article {48955,
	title = {Regioselective synthesis of benzannulated [5,6]-oxaspirolactones via Cu(II)-catalyzed cycloisomerization of 2-(5-Hydroxyalkynyl)benzoates},
	journal = {Journal of Organic Chemistry },
	volume = {88},
	year = {2023},
	month = {NOV},
	pages = {16915-16933},
	type = {Article},
	abstract = {<p>Spiroketals and oxaspirolactones are widely found in biologically active natural products, serving as important structural motifs. In this study, we present a Cu-(II)-catalyzed cascade cycloisomerization of 2-(5-hydroxyalkynyl)-benzoates, enabling the regioselective synthesis of benzannulated [5,6]-oxaspirolactones containing an isochromen-1-one moiety. This strategy offers a rapid and efficient approach to access a diverse array of benzannulated [5,6]-oxaspirolactones. The methodology presented here showcases a broad substrate scope, delivering good yields and scalability up to gram scale. The structures of the oxaspirolactones were unequivocally confirmed through single-crystal X-ray analysis and by analogy using H-1 and C-13-{H-1} NMR data.</p>
},
	keywords = {Construction, Isocumarins, Strategies},
	issn = {0022-3263},
	doi = {10.1021/acs.joc.3c01751},
	author = {Thorat, Sagar S. and Shimpi, Sagar P. and Sambherao, Pooja I. and Krishna, Gamidi Rama and Kontham, Ravindar}
}
