An enantioselective sulfenylation/semipinacol rearrangement of 1,1-disubstituted and trisubstituted allylic alcohols was accomplished with ac hiral Lewis base and ac hiral Brønsted acid as cocatalysts,g enerating various b-arylthio ketones bearing an all-carbon quaternary center in moderate to excellent yields and excellent enantioselectivities.T hese chiral arylthio ketone products are common intermediates with many applications,for example,inthe design of new chiral catalysts/ ligands and the total synthesis of natural products.C omputational studies (DFT calculations) were carried out to explain the enantioselectivity and the role of the chiral Brønsted acid. Additionally,t he synthetic utility of this method was exemplified by an enantioselective total synthesis of (À)-herbertene and aone-pot synthesis of achiral sulfoxide and sulfone. Figure 3. Energy profiles for the enantioselective sulfenylation/semipinacol rearrangement of 1,1-disubstituted allylic alcohol 3a after formation of 12 a.Bond lengths are given in . Angewandte Chemie Communications
Enantioselective
synthesis of axially chiral sulfur-containing
biaryl derivatives through the electrophilic sulfenylation of biaryl
phenols has been achieved for the first time. This catalytic asymmetric
system, which involves sequential desymmetrization and kinetic resolution,
is enabled by a combination of a novel 3,3′-disubstituted BINOL-derived
selenide catalyst and an achiral sulfonic acid. Control experiments
and computational studies suggest that multiple noncovalent interactions
between the cocatalysts and substrate, especially a network of hydrogen
bond interactions, play a crucial role in determining the enantioselectivity
and reactivity.
Enantioselective intermolecular three-component oxysulfenylations of alkenes with phenols and alcohols as O-nucleophiles were achieved using chiral BINAM-derived sulfide/phosphoric acid as the cocatalyst. Notably, chiral BINAM-derived sulfide/phosphoric acid co-catalysis was first explored to successfully catalyze highly enantioselective transformation. A variety of sulfurcontaining benzylic aryl ethers and benzylic alkyl ethers, which contain two contiguous chiral stereocenters, were readily obtained in moderate to excellent yields with high to excellent enantioselectivities. This protocol features a broad substrate scope with excellent functional group tolerance and high chemo-, regio-, and enantioselectivity. Computational studies were performed to explain the origin of the high selectivity. Additionally, the calculation results indicate that commonly supposed racemization "olefin-to-olefin" transfer process of thiiranium ion does not occur in this system.
An
enantioselective selenocyclization of 1,1-disubstituted alkenes
was achieved for the first time, which is enabled by a novel combination
of a chiral BINAM-derived sulfide and an achiral Lewis acid. Various
selenium-containing 4H-3,1-benzoxazines, which are
widely present in a range of medicinally relevant molecules, were
readily obtained in moderate to good yields and good to excellent
enantioselectivities. A series of tetrasubstituted carbon stereocenters
were facilely constructed.
An enantioselective sulfenylation/semipinacol rearrangement of 1,1‐disubstituted and trisubstituted allylic alcohols was accomplished with a chiral Lewis base and a chiral Brønsted acid as cocatalysts, generating various β‐arylthio ketones bearing an all‐carbon quaternary center in moderate to excellent yields and excellent enantioselectivities. These chiral arylthio ketone products are common intermediates with many applications, for example, in the design of new chiral catalysts/ligands and the total synthesis of natural products. Computational studies (DFT calculations) were carried out to explain the enantioselectivity and the role of the chiral Brønsted acid. Additionally, the synthetic utility of this method was exemplified by an enantioselective total synthesis of (−)‐herbertene and a one‐pot synthesis of a chiral sulfoxide and sulfone.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.