15 research outputs found
New alkene cyclopropanation reactions enabled by photoredox catalysis via radical carbenoids
We describe the recent emergence of a new approach for the synthesis of
cyclopropane rings by means of photoredox catalysis. This methodology relies
on the photocatalytic generation of radical carbenoids or carbenoid-like
radicals as cyclopropanating species, and its characterized by an excellent
functional group tolerance, chemoselectivity and ability to cyclopropane E/Z
alkene mixtures with excellent stereocontrol. The mild reaction conditions and
the employ of user-friendly reagents are highly attractive features that may
find immediate use in academic and industrial laboratories
A transition-metal-free & diazo-free styrene cyclopropanation
An operationally simple and broadly applicable novel cyclopropanation of styrenes using gem-diiodomethyl carbonyl reagents has been developed. Visible-light triggered the photoinduced generation of iodomethyl carbonyl radicals, able to cyclopropanate a wide array of styrenes with excellent chemoselectivity and functional group tolerance. To highlight the utility of our photocyclopropanation, we demonstrated the late-stage functionalization of biomolecule derivatives
A Stereoconvergent Cyclopropanation Reaction of Styrenes
The first stereoconvergent cyclopropanation reaction by means of photoredox catalysis using diiodomethane as methylene source is described. This transformation exhibits broad functional group tolerance and it is characterized by an excellent stereocontrol en route to trans-cyclopropanes regardless of whether E- or Z-styrene substrates were utilized
A Stereoconvergent Cyclopropanation Reaction of Styrenes
The first stereoconvergent cyclopropanation reaction by means of photoredox catalysis using diiodomethane as methylene source is described. This transformation exhibits broad functional group tolerance and it is characterized by an excellent stereocontrol en route to trans-cyclopropanes regardless of whether E- or Z-styrene substrates were utilized
Chiral Cyclopentadienyl Ligands: Design, Syntheses, and Applications in Asymmetric Catalysis
The creation of new chiral ligands capable of providing high stereocontrol in metal-catalyzed reactions is crucial in modern organic synthesis. The production of bioactive molecules as single enantiomers is increasingly required, and asymmetric catalysis with metal complexes constitutes one of the most efficient synthetic strategies to access optically active compounds. Herein we offer a historical overview on the development of chiral derivatives of the ubiquitous cyclopentadienyl ligand (Cp-X), and detail their successful application in a broad range of metal-catalyzed transformations. Those include the functionalization of challenging C-H bonds and beyond, giving access to an extensive catalogue of valuable chiral molecules. A critical comparison of the existing ligand families, their design, synthesis, and complexation to different metals is also provided. In addition, future research directions are discussed to further enhance the performance and application of Cp-X ligands in enantioselective catalysis
Risk of cancer in family members of patients with lynch-like syndrome
Lynch syndrome (LS) is a common cause of hereditary colorectal cancer (CRC). Some CRC
patients develop mismatch repair deficiency without germline pathogenic mutation, known as
Lynch-like syndrome (LLS). We compared the risk of CRC in first-degree relatives (FDRs) in LLS and
LS patients. LLS was diagnosed when tumors showed immunohistochemical loss of MSH2, MSH6,
and PMS2; or loss of MLH1 with BRAF wild type; and/or no MLH1 methylation and absence of
pathogenic mutation in these genes. CRC and other LS-related neoplasms were followed in patients
diagnosed with LS and LLS and among their FDRs. Standardized incidence ratios (SIRs) were
calculated for CRC and other neoplasms associated with LS among FDRs of LS and LLS patients.
In total, 205 LS (1205 FDRs) and 131 LLS families (698 FDRs) had complete pedigrees. FDRs of
patients with LLS had a high incidence of CRC (SIR, 2.08; 95% confidence interval (CI), 1.56–2.71),
which was significantly lower than that in FDRs of patients with LS (SIR, 4.25; 95% CI, 3.67–4.90;
p < 0.001). The risk of developing other neoplasms associated with LS also increased among FDR
of LLS patients (SIR, 2.04; 95% CI, 1.44–2.80) but was lower than that among FDR of patients with
LS (SIR, 5.01, 95% CI, 4.26–5.84; p < 0.001). FDRs with LLS have an increased risk of developing
CRC as well as LS-related neoplasms, although this risk is lower than that of families with LS. Thus,
their management should take into account this increased risk
Risk of cancer in family members of patients with lynch-like syndrome
Lynch syndrome (LS) is a common cause of hereditary colorectal cancer (CRC). Some CRC
patients develop mismatch repair deficiency without germline pathogenic mutation, known as
Lynch-like syndrome (LLS). We compared the risk of CRC in first-degree relatives (FDRs) in LLS and
LS patients. LLS was diagnosed when tumors showed immunohistochemical loss of MSH2, MSH6,
and PMS2; or loss of MLH1 with BRAF wild type; and/or no MLH1 methylation and absence of
pathogenic mutation in these genes. CRC and other LS-related neoplasms were followed in patients
diagnosed with LS and LLS and among their FDRs. Standardized incidence ratios (SIRs) were
calculated for CRC and other neoplasms associated with LS among FDRs of LS and LLS patients.
In total, 205 LS (1205 FDRs) and 131 LLS families (698 FDRs) had complete pedigrees. FDRs of
patients with LLS had a high incidence of CRC (SIR, 2.08; 95% confidence interval (CI), 1.56–2.71),
which was significantly lower than that in FDRs of patients with LS (SIR, 4.25; 95% CI, 3.67–4.90;
p < 0.001). The risk of developing other neoplasms associated with LS also increased among FDR
of LLS patients (SIR, 2.04; 95% CI, 1.44–2.80) but was lower than that among FDR of patients with
LS (SIR, 5.01, 95% CI, 4.26–5.84; p < 0.001). FDRs with LLS have an increased risk of developing
CRC as well as LS-related neoplasms, although this risk is lower than that of families with LS. Thus,
their management should take into account this increased risk