The development of
a scalable asymmetric route to a new calcitonin
gene-related peptide (CGRP) receptor antagonist is described. The
synthesis of the two key fragments was redefined, and the intermediates
were accessed through novel chemistry. Chiral lactam 2 was prepared by an enzyme mediated dynamic kinetic transamination
which simultaneously set two stereocenters. Enzyme evolution resulted
in an optimized transaminase providing the desired configuration in
>60:1 syn/anti. The final chiral
center was set via a crystallization induced diastereomeric transformation.
The asymmetric spirocyclization to form the second fragment, chiral
spiro acid intermediate 3, was catalyzed by a novel doubly
quaternized phase transfer catalyst and provided optically pure material
on isolation. With the two fragments in hand, development of their
final union by amide bond formation and subsequent direct isolation
is described. The described chemistry has been used to deliver over
100 kg of our desired target, ubrogepant.
In recent years, as the amount of seismic data has grown rapidly, it is very important to develop a fast and reliable event detection and association algorithm. Generally, event detection is first performed on individual stations followed by event association through linking phase arrivals to a common event generating them. This study considers earthquake detection as the problem of image classification and convolutional neural networks (CNNs), as some of the widely used deep-learning tools in image processing, can be well used to solve this problem. In contrast to existing studies training the network using seismic data from individual stations, in this study, we train a CNN model jointly using records of multiple stations. Because the CNN automatically synthesizes information among multiple stations, the detector can more reliably detect seismic events and is less affected by spurious signals. The CNN is trained using aftershock data of the 2013 Mw 6.6 Lushan earthquake. We have applied it on two very different datasets of Gofar transform fault, East Pacific Rise and Changning shale gas field in southern Sichuan basin, China. The tests show that the trained CNN has strong generalization ability and is flexible with the number of available stations, different instrument types, and different data sampling rates. It can detect many more events than the conventional short-term average/long-term average detector and is more efficient than template-matching methods.
A scalable and efficient synthesis of the GPR40 agonist MK-8666 was developed from a simple pyridine building block. The key step to set the stereochemistry at two centers relied on an enzymatic dynamic kinetic reduction of an unactivated ketone. Directed evolution was leveraged to generate an optimized ketoreductase that provided the desired trans alcohol in >30:1 dr and >99% ee. Further, it was demonstrated that all four diastereomers of this hydroxy-ester could be prepared in high yield and selectivity. Subsequently, a challenging intramolecular displacement was carried out to form the cyclopropane ring system with perfect control of endo/exo selectivity. The endgame coupling strategy relied on a Pd-catalyzed C-O coupling to join the headpiece chloropyridine with the benzylic alcohol tailpiece.
An efficient route to the HCV antiviral agent uprifosbuvir was developed in 5 steps from readily available uridine in 50% overall yield. This concise synthesis was achieved by development of...
Cholesteryl
ester transfer protein (CETP) represents one of the
key regulators of the homeostasis of lipid particles, including high-density
lipoprotein (HDL) and low-density lipoprotein (LDL) particles. Epidemiological
evidence correlates increased HDL and decreased LDL to coronary heart
disease (CHD) risk reduction. This relationship is consistent with
a clinical outcomes trial of a CETP inhibitor (anacetrapib) combined
with standard of care (statin), which led to a 9% additional risk
reduction compared to standard of care alone. We discuss here the
discovery of MK-8262, a CETP inhibitor with the potential for being
the best-in-class molecule. Novel in vitro and in vivo paradigms were
integrated to drug discovery to guide optimization informed by a critical
understanding of key clinical adverse effect profiles. We present
preclinical and clinical evidence of MK-8262 safety and efficacy by
means of HDL increase and LDL reduction as biomarkers for reduced
CHD risk.
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