@article { ISI:000340525300012,
	title = {Synthesis of alpha,beta-unsaturated delta-lactones by vinyl acetate mediated asymmetric cross-aldol reaction of acetaldehyde: mechanistic insights},
	journal = {European Journal of Organic Chemistry},
	number = {24},
	year = {2014},
	month = {AUG},
	pages = {5247-5255},
	publisher = {WILEY-V C H VERLAG GMBH},
	type = {Article},
	address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY},
	abstract = {<p>A tandem asymmetric cross-aldol reaction involving the in situ generation of acetaldehyde from vinyl acetate has been developed that may resolve the challenges associated with the handling of acetaldehyde. The simple protocol, mild reaction conditions and unique harmony of an organocatalyst with a biocatalyst make this method a valuable tool for the synthesis of asymmetric beta-hydroxy aldehydes. By using this methodology we have accessed alpha,beta-unstaurated delta-lactones as well as isochromenones with high enantioselectivities from both asymmetric beta-hydroxy aldehydes and ketones. Systemic density functional theory (DFT) studies were also performed to gain mechanistic insights into the role of hydrogen bonding in the asymmetric cross-aldol reaction of acetaldehyde and in the key cis/trans isomerisation step in the synthesis of d-lactones.</p>},
	keywords = {Aldol reactions, asymmetric catalysis, lactones, reaction mechanisms},
	issn = {1434-193X},
	doi = {10.1002/ejoc.201402551},
	author = {Kumar, Manjeet and Kumar, Arvind and Rizvi, Masood and Mane, Manoj and Vanka, Kumar and Taneja, Subhash C. and Shah, Bhahwal Ali}
}
@article {48714,
	title = {"Weak" C-H{\textbullet}{\textbullet}{\textbullet}S interaction drives enantioselectivity in cinchona alkaloid complex catalyzed thiocyanation},
	journal = {Chemistry-An Asian Journal},
	volume = {18},
	year = {2023},
	month = {JUL},
	pages = {e202300321},
	type = {Article},
	abstract = {<p>
	The great success of asymmetric organocatalysis has made it one of the most important advancements made in chemistry in the past two decades. A significant achievement in this context is the asymmetric organocatalysis of the thiocyanation reaction. In the current study, computational studies with density functional theory have been done in order to understand an interesting experimental finding: the reversal of enantioselectivity from R to S when the electrophile is changed from beta-keto ester to oxindole for the thiocyanation reaction with the cinchona alkaloid complex catalyst. The calculations reveal an unusual fact - the principal reason for the reversal is the presence of the C-H center dot center dot center dot S noncovalent interaction, which is present only in the major transition states in each of the two nucleophile cases. Only recently has it been realized that the supposedly weak C-H center dot center dot center dot S noncovalent interaction has the properties of a hydrogen bond, and the fact that this interaction is the cause of enantioselectivity has relevance, because of the large number of asymmetric transformations involving the sulphur heteroatom.</p>
},
	keywords = {Density functional calculations, Enantioselectivity, noncovalent interactions, organocatalysis, reaction mechanisms},
	issn = {1861-4728},
	doi = {10.1002/asia.202300321},
	author = {Banerjee, Subhrashis and Vanka, Kumar}
}
