@article {43875,
	title = {Lewis acid catalyzed cascade annulation of alkynols with alpha-ketoesters: a facile access to gamma-spiroketal-gamma-lactones},
	journal = {Chemical Communications},
	volume = {53},
	year = {2017},
	month = {JUN},
	pages = {6641-6644},
	type = {Article},
	abstract = {A novel Lewis acid catalyzed intermolecular cascade annulation of alkynols with alpha-ketoesters has been developed. This simple and efficient cascade annulation proceeds through a 5-exo-dig cyclization of alkynols followed by annulation with alpha-ketoester to provide a wide variety of unsaturated gamma-spiroketal-gamma-lactones (1,6-dioxaspiro[4.4]non-3-en-2-ones) related to many natural products.},
	doi = {10.1039/c7cc03668j},
	author = {Kambale, Digambar A. and Thorat, Sagar S. and Pratapure, Madhukar S. and Gonnade, Rajesh G. and Kontham, Ravindar}
}
@article {47633,
	title = {Bismuth(iii)-catalyzed bis-cyclization of propargylic diol-esters: a unified approach for the synthesis of [5,5]- and [6,5]-oxaspirolactones},
	journal = {Organic \& Biomolecular Chemistry},
	volume = {19},
	year = {2021},
	month = {AUG },
	pages = {6618-6622},
	type = {Article},
	abstract = {Herein we disclose an unprecedented intramolecular cascade strategy for the construction of alpha,beta-unsaturated [5,5]- and [6,5]-oxaspirolactones that capitalizes on the pi-electrophilic Lewis acid-catalyzed 5-exo-dig or 6-exo-dig mode of cyclization of propargylic diol esters, followed by dehydration and spirolactonization steps. Moreover, semi-protected substrates also delivered the respective oxaspirolactones with the same ease and in appreciable yields under optimal reaction conditions.},
	issn = {1477-0520},
	doi = {10.1039/d1ob00974e},
	author = {Kambale, Digambar A. and Borade, Balasaheb R. and Kontham, Ravindar}
}
@article {48722,
	title = {Divergent synthesis of oxepino-phthalides and [5,5]-oxaspirolactones through [2+2+2]- and [2+3]-annulation of alkynyl alcohols with a-ynone-esters},
	journal = {Journal of Organic Chemistry},
	volume = {88},
	year = {2023},
	month = {AUG },
	pages = {12597-12612},
	type = {Article},
	abstract = {<p>
	Unmasking the synthetic potential of alkyne functional group of alkynyl alcohols as surrogates of carbonyl compounds, herein we present the first Bronsted acid (TfOH)-catalyzed [2 + 2 + 2]-annulation of 4-pentyn-1-ols (possessing terminal alkyne) with a-ynone-esters to access tricyclic tetrahydro-oxepino-phthalides. Besides, an unprecedented synthesis of a-acetoaryl or a-alkynyl [5,5]-oxaspirolactones has been demonstrated by employing 4-pentyn-1-ols (possessing an internal alkyne) as an annulation partner, which proceeds through a divergent [2 + 3]-annulation pathway.</p>
},
	issn = {0022-3263},
	doi = {10.1021/acs.joc.3c01301},
	author = {Kambale, Digambar A. and Borade, Balasaheb R. and Vinodkumar, Ramavath and Kontham, Ravindar}
}
