Highly diastereo- and branched-selective rearrangement of substituted -alloc--allyl ynamides.

An auto-tandem catalytic, branched-selective rearrangement of substituted -alloc--allyl ynamides was developed. This reaction provides ready access to complex quaternary nitrile products with vinylogous stereocentres in excellent diastereoselectivity, including contiguous all-carbon quaternary centres. The stereochemical outcome is determined a Pd(0) catalysed dipolar ketenimine aza-Claisen rearrangement and computational studies exemplify the key role ligand geometry plays.

Design, synthesis and biological evaluation of novel O-substituted tryptanthrin oxime derivatives as c-Jun -terminal kinase inhibitors.

The c-Jun -terminal kinase (JNK) family includes three proteins (JNK1-3) that regulate many physiological processes, including inflammatory responses, morphogenesis, cell proliferation, differentiation, survival, and cell death. Therefore, JNK represents an attractive target for therapeutic intervention. Herein, a panel of novel tryptanthrin oxime analogs were synthesized and evaluated for JNK1-3 binding (K) and inhibition of cellular inflammatory responses (IC).

A Highly Stereospecific Claisen-Sakurai Approach to Densely Functionalized Cyclopentenols.

The formation of highly substituted cyclopentenols was developed using a Claisen-Sakurai reaction. Both elements of the reaction can be performed in a one-pot sequence that provides the corresponding cyclized products in high stereoselectivity. The stereochemical outcome is defined by a combination of Claisen stereospecificity and stereoelectronic effects in the Sakurai cyclization that promotes reactivity via an -S' antiperiplanar transition state.

Pd-Catalyzed Rearrangement of -Alloc--allyl Ynamides Auto-Tandem Catalysis: Evidence for Reversible C-N Activation and Pd(0)-Accelerated Ketenimine Aza-Claisen Rearrangement.

An auto-tandem catalytic double allylic rearrangement of -alloc--allyl ynamides was developed. This reaction proceeds through two separate and distinct catalytic cycles with both decarboxylative Pd-π-allyl and Pd(0)-promoted aza-Claisen rearrangements occurring. A detailed mechanistic study supported by computations highlights these two separate mechanisms.

Singapore's Pandemic Preparedness: An Overview of the First Wave of COVID-19.

A global response to the rapid spread of the 2019 novel coronavirus disease (COVID-19) is imperative in order to reduce mortality and morbidity as well as preventing a country's health system from collapse. Singapore showed exceptional leadership in the containment of the spread of the virus, however through April 2020 the country experienced exponential growth in the number of infections, particularly migrant workers living in dormitories. The following historical case study provides an overview of Singapore's country profile, their healthcare system and the country's non pharmaceutical measures taken to mitigate and contain the spread of COVID-19 in the first few months of the pandemic.

COVID-19 Down Under: Australia's Initial Pandemic Experience.

The following case study aims to provide a broad overview of the initial Australian epidemiological situation of the novel coronavirus disease (COVID-19) pandemic. We provide a case presentation of Australia's current demographic characteristics and an overview of their health care system. The data we present on Australia's COVID-19 situation pertain to the initial wave of the pandemic from January through to 20 April 2020.

Coumarin Partitioning in Model Biological Membranes: Limitations of log as a Predictor.

Time-resolved fluorescence measurements were used to quantify partitioning of three different 7-aminocoumarin derivatives into DPPC vesicle bilayers as a function of temperature. The coumarin derivatives were structurally equivalent except for the degree of substitution at the 7-amine position. Calculated log  (octanol: water partitioning) coefficients, a common indicator that correlates with bioconcentration, predict that the primary amine (coumarin 151 or C151) would experience a ∼40-fold partition enrichment in polar organic environments (log  = 1.

Facilitating accurate health provider directories using natural language processing.

Background: Accurate information in provider directories are vital in health care including health information exchange, health benefits exchange, quality reporting, and in the reimbursement and delivery of care. Maintaining provider directory data and keeping it up to date is challenging. The objective of this study is to determine the feasibility of using natural language processing (NLP) techniques to combine disparate resources and acquire accurate information on health providers.

Formation of Ketenimines via the Palladium-Catalyzed Decarboxylative π-Allylic Rearrangement of N-Alloc Ynamides.

A new approach for the formation of ketenimines via a decarboxylative allylic rearrangement pathway that does not require strong stabilizing or protecting groups has been developed. The products can be readily hydrolyzed into their corresponding secondary amides or reacted with sulfur ylides to perform an additional [2,3]-Wittig process. Mechanistic studies suggest an outer-sphere process in which reductive alkylation is rate-limiting.

E-band Nd amplifier based on wavelength selection in an all-solid micro-structured fiber.

A Nd fiber amplifier with gain from 1376 nm to 1466 nm is demonstrated. This is enabled by a wavelength selective waveguide that suppresses amplified spontaneous emission between 850 nm and 1150 nm. It is shown that while excited state absorption (ESA) precludes net gain below 1375 nm with the exception of a small band from 1333 nm to 1350 nm, ESA diminishes steadily beyond 1375 nm allowing for the construction of an efficient fiber amplifier with a gain peak at 1400 nm and the potential for gain from 1375 nm to 1500 nm.

Palladium-catalyzed oxidative synthesis of highly functionalized ortholactones.

A palladium-catalyzed oxidative reaction is reported which converts dihydropyrans to their corresponding ortholactone. The products are formed in good to excellent yields with a very high level of chemoselectivity and functional group tolerance. Mechanistic studies confirm that the reaction proceeds by a Wacker-type mechanism.

Base-mediated cascade rearrangements of aryl-substituted diallyl ethers.

Two base-mediated cascade rearrangement reactions of diallyl ethers were developed leading to selective [2,3]-Wittig-oxy-Cope and isomerization-Claisen rearrangements. Both diaryl and arylsilyl-substituted 1,3-substituted propenyl substrates were examined, and each exhibits unique reactivity and different reaction pathways. Detailed mechanistic and computational analysis was conducted, which demonstrated that the role of the base and solvent was key to the reactivity and selectivity observed.

MIDA-vinylsilanes: selective cross-couplings and applications to the synthesis of functionalized stilbenes.

A rapid and stereodefined synthesis of MIDA-boryl vinylsilanes has been achieved through the hydrosilylation of an alkynylboronic ester. The E products which contain a silyl and boryl group can be selectively cross-coupled in a two-step bidirectional sequence to provide a rapid and high-yielding synthesis of complex styrenes.

Silicon-directed rhenium-catalyzed allylic substitutions with N-hydroxycarbamates, N-hydroxysulfonamides, and hydroxamic acids.

A rhenium-catalyzed N-selective allylic amination reaction of N-hydroxycarbamates has been developed. This reaction occurs with excellent N/O selectivity and with complete carbon selectivity on the allylic system. The reaction is tolerant of many functional groups and also proceeds with N-hydroxysulfonamides and hydroxamic acids.

Silicon-directed rhenium-catalyzed allylic carbaminations and oxidative fragmentations of γ-silyl allylic alcohols.

A highly regioselective allylic substitution of β-silyl allylic alcohols has been achieved that provides the branched isomer as a single product. This high level of regiocontrol is achieved through the use of a vinyl silane group that can perform a Hiyama coupling providing 1,3-disubstituted allylic amines. An unusual oxidative fragmentation product was also observed at elevated temperature that appears to proceed by a Fleming-Tamao-type oxidation-elimination pathway.

Highly diastereoselective hydrosilylations of allylic alcohols.

The highly syn-selective hydrosilylation of allylic alcohols was developed which, following oxidation, provided 1,3 alcohols containing two contiguous stereocentres. Through judicious choice of silane the complementary anti-selective hydrosilylation was also developed. This protocol was applied to the synthesis of an all syn polyketide stereotriad.

NaH mediated isomerisation-allylation reaction of 1,3-substituted propenols.

A base mediated isomerisation-allylation protocol of 1,3-disubstituted propenols has been established. The use of diaryl and aryl-silyl substrates is reported alongside the use of substituted allyl bromides. Mechanistic experiments have also been conducted to elucidate the reaction pathway.

Copper/TEMPO catalysed synthesis of nitriles from aldehydes or alcohols using aqueous ammonia and with air as the oxidant.

Copper/TEMPO catalysts can be used to prepare nitriles from aldehydes or alcohols using aqueous ammonia. Readily accessible methods were developed that enable standard glassware to be used with air as the source of O2. It was further shown that, at higher temperatures in a pressurised reactor under limiting oxygen conditions (8% O2), catalyst loadings of 1 mol% could be employed.

Platinum catalysed hydrosilylation of propargylic alcohols.

A facile and user-friendly protocol has been developed for the selective synthesis of E-vinyl silanes derived from propargylic alcohols using a PtCl2/XPhos catalyst system. The reaction is generally high yielding and provides a single regioisomer at the β-position with E-alkene geometry. The reaction is extremely tolerant of functionality and has a wide scope of reactivity both in terms of alkynes and silanes used.

Palladium catalyzed decarboxylative rearrangement of N-alloc indoles.

A highly efficient palladium catalyzed decarboxylative allylic rearrangement of alloc indoles has been developed. This can also be combined with a Suzuki-Miyaura cross-coupling reaction in a single pot transformation. Substituted alloc groups and benzylic variants have also been demonstrated alongside promising initial results on the enantioselective variant.

Domino alkene-isomerization-Claisen rearrangement strategy to substituted allylsilanes.

A one-pot isomerization-Claisen protocol has been developed for the synthesis of highly substituted allylsilanes. Monosilylated divinyl ethers can be isomerized using a cationic iridium(I) catalyst followed by a thermal Claisen rearrangement to provide the allylsilanes in excellent yields and diastereoselectivities.

PtCl2/XPhos: a highly efficient and readily available catalyst for the hydrosilylation of propargylic alcohols.

A highly regioselective hydrosilylation of propargylic alcohols has been developed using an in situ prepared PtCl(2)/XPhos catalyst system. The reaction is tolerant of many functional groups and exhibits excellent regio and geometric selectivity.