@article { ISI:000369587800022, title = {Ammonium catalyzed cyclitive additions: evidence for a cation-pi interaction with alkynes}, journal = {Chemical Communications}, volume = {52}, number = {11}, year = {2016}, month = {DEC}, pages = {2311-2313}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The addition of carbamate nitrogen to a non-conjugated carbon-carbon triple bond is catalyzed by an ammonium salt leading to a cyclic product. Studies in homogeneous systems suggest that the ammonium agent facilitates nitrogen-carbon bond formation through a cation-p interaction with the alkyne unit that, for the first time, is directly observed by Raman spectroscopy.

}, issn = {1359-7345}, doi = {10.1039/c5cc08641h}, author = {Nagy, Edith and St Germain, Elijah and Cosme, Patrick and Maity, Pradip K. and Terentis, Andrew C. and Lepore, Salvatore D.} } @article {46337, title = {Allenoate prenucleophiles: a triply diastereoselective approach to beta-hydroxy esters containing all-carbon alpha-quaternary centers}, journal = {Organic Letters}, volume = {21}, year = {2019}, month = {OCT }, pages = {7952-7955}, type = {Article}, abstract = {

Allenyl esters activated by titanium(IV) underwent additions to a wide range of aldehydes in high regio- and diastereoselectivities leading to products containing an all carbon quaternary center bearing an alpha-vinyl group that was installed with high selectivity for the Z-geometry. An aldol product was also converted to an indanone offering a new route to this important compound class. Product triple diastereoselectivity has been rationalized using a concerted transition-state model.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.9b02930}, author = {Maki, Samantha L. and Maity, Pradip and Dougherty, Shannon and Johns, Jennifer and Lepore, Salvatore D.} } @article {49912, title = {Anionic 5-endo-dig cyclizations: an experimental investigation of in-plane aromaticity involving a non-enolate carbanion nucleophile}, journal = {Organic Chemistry Frontiers}, volume = {12}, year = {2025}, month = {NOV}, pages = {6609-6613}, type = {Article}, abstract = {

Cyclitive additions of aliphatic carbanions to non-electrophilic carbon-carbon triple bonds under mild, transition-metal-free conditions are described for the first time. These results confirm theoretical models that invoke in-plane aromaticity to predict the favorability of 5-endo-dig reactions in these systems. In contrast to related Conia-ene cyclizations (5-enolexo-endo-dig), our results generally led to cyclic and allene products in near parity ratios across a broad range of substrates, suggesting that cyclization may proceed via an early ambimodal transition state. Experimental results are presented with a view to refining existing mechanistic models for this growing class of alkyne reactions.

}, doi = {10.1039/d5qo00547g}, author = {Nugent, Kristina M. and Hintze, Silas Q. and Maity, Pradip and Lepore, Salvatore D.} }