7 research outputs found
Copper-Catalyzed S<sub>N</sub>2′-Selective Allylic Substitution Reaction of <i>gem</i>-Diborylalkanes
A Cu/(NHC)-catalyzed
S<sub>N</sub>2′-selective substitution
reaction of allylic electrophiles with <i>gem</i>-diborylalkanes
is reported. Different substituted <i>gem</i>-diborylalkanes
and allylic electrophiles can be employed in this reaction, and various
synthetic valuable functional groups can be tolerated. The asymmetric
version of this reaction was initially researched with chiral N-heterocyclic
carbene (NHC) ligands
Exploration of Biaryl Carboxylic Acids as Proton Shuttles for the Selective Functionalization of Indole C–H Bonds
A survey
of diversely substituted 2-arylbenzoic acids were synthesized
and tested for use as proton shuttle in the direct arylation of indoles
with bromobenzenes. It was found that 3-ethoxy-2-phenylbenzoic acid
gives superior yield and selectivity for this class of substrates
Data_Sheet_1_Clustering and prediction of disease progression trajectories in Huntington's disease: An analysis of Enroll-HD data using a machine learning approach.docx
IntroductionHuntington's disease (HD) is a rare neurodegenerative disease characterized by cognitive, behavioral and motor symptoms that progressively worsen with time. Cognitive and behavioral signs of HD are generally present in the years prior to a diagnosis; however, manifest HD is typically assessed by genetic confirmation and/or the presence of unequivocal motor symptoms. Nevertheless, there is a large variation in symptom severity and rate of progression among individuals with HD.MethodsIn this retrospective study, longitudinal natural history of disease progression was modeled in individuals with manifest HD from the global, observational Enroll-HD study (NCT01574053). Unsupervised machine learning (k-means; km3d) was used to jointly model clinical and functional disease measures simultaneously over time, based on one-dimensional clustering concordance such that individuals with manifest HD (N = 4,961) were grouped into three clusters: rapid (Cluster A; 25.3%), moderate (Cluster B; 45.5%) and slow (Cluster C; 29.2%) progressors. Features that were considered predictive of disease trajectory were then identified using a supervised machine learning method (XGBoost).ResultsThe cytosine adenine guanine-age product score (a product of age and polyglutamine repeat length) at enrollment was the top predicting feature for cluster assignment, followed by years since symptom onset, medical history of apathy, body mass index at enrollment and age at enrollment.ConclusionsThese results are useful for understanding factors that affect the global rate of decline in HD. Further work is needed to develop prognostic models of HD progression as these could help clinicians with individualized clinical care planning and disease management.</p
Copper-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides and Tosylates with Secondary Alkyl Grignard Reagents
Practical catalytic cross-coupling of secondary alkyl
electrophiles
with secondary alkyl nucleophiles under Cu catalysis has been realized.
The use of TMEDA and LiOMe is critical for the success of the reaction.
This cross-coupling reaction occurs via an S<sub>N</sub>2 mechanism
with inversion of configuration and therefore provides a general approach
for the stereocontrolled formation of C–C bonds between two
tertiary carbons from chiral secondary alcohols
Copper-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides and Tosylates with Secondary Alkyl Grignard Reagents
Practical catalytic cross-coupling of secondary alkyl
electrophiles
with secondary alkyl nucleophiles under Cu catalysis has been realized.
The use of TMEDA and LiOMe is critical for the success of the reaction.
This cross-coupling reaction occurs via an S<sub>N</sub>2 mechanism
with inversion of configuration and therefore provides a general approach
for the stereocontrolled formation of C–C bonds between two
tertiary carbons from chiral secondary alcohols
Copper-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides and Tosylates with Secondary Alkyl Grignard Reagents
Practical catalytic cross-coupling of secondary alkyl
electrophiles
with secondary alkyl nucleophiles under Cu catalysis has been realized.
The use of TMEDA and LiOMe is critical for the success of the reaction.
This cross-coupling reaction occurs via an S<sub>N</sub>2 mechanism
with inversion of configuration and therefore provides a general approach
for the stereocontrolled formation of C–C bonds between two
tertiary carbons from chiral secondary alcohols
Stereoselective Synthesis of Monofluoroalkenylphosphine Oxides via Photoinduced Decarboxylative Coupling of α‑Fluoroacrylic Acids with P(O)H Compounds
Herein,
a practical and efficient method for synthesizing monofluoroalkenyl
phosphine oxides via photoinduced decarboxylative/dehydrogenative
coupling of α-fluoroacrylic acids with phosphine oxides and
phosphonates has been developed. Various α-fluoroacrylic acids
and P(O)H compounds containing relevant functional groups, including
tetrafluorobenzene and pentafluorobenzene, were converted into corresponding
products with excellent E-stereoselectivity in satisfactory
yields. This method can be extended to achieve the synthesis of monofluoroalkenyl
silanes under similar conditions