An efficient Pd(II)-catalyzed oxidative olefination of phenols bearing removable directing groups with molecular oxygen as the sole oxidant has been developed. This reaction protocol provides an efficient and robust synthetic tool for the synthesis of o-alkenyl phenols under mild conditions.

An improved and practical procedure for the stereoselective synthesis of anti-β-hydroxy-α-amino acids (anti-βhAAs), by palladium-catalyzed sequential C(sp(3) )-H functionalization directed by 8-aminoquinoline auxiliary, is described. followed by a previously established monoarylation and/or alkylation of the β-methyl C(sp(3) )-H of alanine derivative, β-acetoxylation of both alkylic and benzylic methylene C(sp(3) )-H bonds affords various anti-β-hydroxy-α-amino acid derivatives. As an example, the synthesis of β-mercapto-α-amino acids, which are highly important to the extension of native chemical ligation chemistry beyond cysteine, is described. The synthetic potential of this protocol is further demonstrated by the synthesis of diverse β-branched α-amino acids. The observed diastereoselectivities are strongly influenced by electronic effects of aromatic AAs and steric effects of the linear side-chain AAs, which could be explained by the competition of intramolecular C-OAc bond reductive elimination from Pd(IV) intermediates vs. intermolecular attack by an external nucleophile (AcO(-) ) in an SN 2-type process.

A Pd(ii)-catalyzed oxidative alkoxycarbonylation of phenol derivatives with atmospheric pressure of CO-O2 and alcohols has been achieved. The reaction provides an efficient strategy for the synthesis of carboxylic esters and can be applied to the late-stage modification of complex molecules.

No abstract

After total knee arthroplasty, LMWH-p is safer for bleeding than LMWH-s and equally effective concerning prevention of DVT.

The objective of this research is to experimentally investigate the transient operating characteristics of a titaniumwater loop heat pipe subjected to a combined steady-state evaporator input heat rate and a steady-periodic acceleration field. For this experimental investigation, a steady-periodic acceleration field, in the form of a sine wave, was generated using a centrifuge table. Radial acceleration peak-to-peak values and frequency of the sine wave were defined prior to conducting each experimental run and ranged from 0.5 g ≤ ar ≤ 10.0 g and 0.01 Hz ≤ f ≤ 0.1 Hz, respectively. Evaporator input heat rate and condenser cold plate coolant temperature were varied, 300 W ≤ Qin ≤ 600 W and 30°C ≤ Tcp ≤ 56°C, respectively. In some cases, acceleration driven forces complimented the thermodynamic forces, improving loop heat pipe dynamical performance. However, the converse was also true in that transient acceleration driven forces also appeared to counter thermodynamic forces or excite natural frequencies of the loop heat pipe. This resulted in immediate failure of the loop heat pipe to operate, delayed failure, or in some cases, the loop heat pipe operated in a stable manner but in a degraded condition. Nomenclature ar = radial acceleration component, g at = tangential acceleration component, g az = vertical acceleration component, g a eff = effective acceleration vector field on the LHP e = coordinate axis unit vector f = acceleration frequency, Hz g = acceleration vector due to gravity g = acceleration vertical component due to gravity, g Q = heat rate, W Qin = input heat rate, W r = position vector r = position vector radial coordinate, m R ref = reference position; accelerometer radial position, 1.208 m (47.56 in.) r 1 = LHP condenser end radial location, 1.219 m (48.0 in.) r 2 = LHP condenser end radial location, 1.215 m (47.82 in.) T = temperature,°C t = time, min or s Tcp = cold plate coolant inlet temperature,°C z r = position vector vertical coordinate, m θ = angular position of the position vector, deg θ 1 = angular position of the position vector at r 1 , 0 deg θ 2 = angular position of the position vector at r 2 , 16.82 deg ω = angular velocity vector ω = angular velocity vector component, rad∕s Subscripts r LHP = radial component of the acceleration vector oriented on the LHP y LHP = radial component of the acceleration vector oriented with the accelerometer x LHP = tangential component of the acceleration vector oriented with the accelerometer z = vertical component of the acceleration vector z LHP = axial component of the acceleration vector oriented on the LHP

The interactions of a spherical flame with an incident shock wave and its reflected shock wave in a confined space were investigated using the three-dimensional reactive Navier-Stokes equations, with emphasis placed on the effect of chemical reactivity of mixture on the flame distortion and detonation initiation after the passage of the reflected shock wave. It is shown that the spatio-temporal characteristics of detonation initiation depend highly on the chemical reactivity of the mixture. When the chemical reactivity enhances, the flame can be severely distorted to form a reactive shock bifurcation structure with detonations initiating at different three-dimensional spatial locations. Moreover, the detonation initiation would occur earlier in a mixture of more enhanced reactivity. The results reveal that the detonations arise from hot spots in the unburned region which are initiated by the shock-detonation-transition mechanism.

Substrates of type (I) bearing a directing 8‐aminoquinoline auxiliary are monoarylated or monoalkylated to afford starting materials such as (IIIa) or (IX).