This manuscript describes the role of non-classical hydrogen bonds (NCHBs), specifically C–H···O interactions, in modern synthetic organic transformations. Our goal is to point out the seminal examples where C–H···O interactions have been invoked as a key stereocontrolling element and to provide predictive value in recognizing future and/or potential C–H···O interactions...
This study describes the combined experimental and computational elucidation of the mechanism and
origins of stereoselectivities in the NHC-catalyzed dynamic kinetic resolution (DKR) of α-substituted-β-ketoesters. Density functional theory computations reveal that the NHC-catalyzed DKR proceeds by two
mechanisms, depending on the stereochemistry around the forming bond: 1) a concerted, asynchronous...
Conspectus:
The flexibility, complexity, and size of contemporary organocatalytic transformations pose interesting and powerful opportunities to computational and experimental chemists alike. In this Account, we disclose our recent computational investigations of three branches of organocatalysis in which nonbonding interactions, such as C–H···O/N interactions, play a crucial role in the organization...
The regiodivergent O- to C- or N-carboxyl transfer of pyrazolyl carbonates is described, with DMAP giving preferential N-carboxylation and triazolinylidenes promoting selective C-carboxylation (both with up to >99 : 1 regioselectivity). An enantioselective O- to C-carboxyl variant using NHC catalysis is demonstrated (up to 92% ee), while mechanistic and DFT studies outline...
My work on computing complex catalyzed organic transformations reveals that only a few subtle chemical factors, e.g. non-classical hydrogen bonding, (hyper)conjugation and steric effects, common across different catalyst manifolds are critical for catalysis and selectivity. Rational manipulation and exploitation of these factors has led to improved catalyst designs, which has...
Prior to the 1930's, little thought was
given to planning for retirement.
Today, retirement planning is built
into employment through social security
and retirement plans so that even
the young employee becomes aware of
retirement and begins making financial
contributions as soon as he starts his
working career. However, it...
OBJECTIVE: In this study, we examined how effectively
people can monitor new stimuli on a peripheral display
while carrying out judgments on an adjacent central display.
BACKGROUND: Improved situation awareness is critical
for improved operator performance in aviation and many
other domains. Given the limited extent of foveal processing,
acquiring...