Item

Abstract

The development of
Brønsted acid catalyzed asymmetric hydrofunctionalizations of unbiased
olefins is described.
In the first part of this thesis, the development of an enantioselective
organocatalytic
intramolecular
hydroalkoxylation
of simple olefins
is presented.
By developing a
new class of sterically confined,
strong
Brønsted
acid catalysts,
various
1,1-disubstituted olefins
were
converted
to the corresponding 2,2-disubsutituted tetrahydrofurans in excellent yields and
enantioselectivities. The method could
also be applied to enantiomerically pure substrates,
enabling
catalyst-controlled diastereoselective cyclizations independent of existing stereogenic centers.
Thorough mechanistic investigations, including both experimental and theoretical analysis, were
conducted in order to elucidate the catalytic
cycle, suggesting an asynchronous concerted
mechanism. In the
second part, the developments of asymmetric organocatalytic hydroarylations
of unbiased olefins
are described.
Various arenes could be used as nucleophiles furnishing
products
with
benzylic all-carbon quaternary
stereocenters
in good yields and enantioselectivities.