Nickel(II)-Catalyzed Formal [3+2] Cycloadditions between Indoles and Donor-Acceptor Cyclopropanes.

This article describes the development of a nickel-catalyzed regio- and diastereoselective formal [3+2] cycloaddition between N-substituted indoles and donor-acceptor cyclopropanes to synthesize cyclopenta[b]indoles. Optimized reaction conditions provide the desired nitrogen-containing cycloadducts in up to 93% yield and dr 8.6:1 with complete regioselectivity. The substrate scope showed high tolerance to various substituted indoles and cyclopropanes, resulting in the synthesis of six new cyclopenta[b]indoles and the isolation of five derivatives previously reported in the literature. In addition, a mechanistic proposal for the reaction was studied through online reaction monitoring by ESI-MS, allowing for the identification of the reactive intermediates in the Ni(II) catalyzed process. X-ray crystallography confirmed the structure and relative endo stereochemistry of the products. This method enables the fast and efficient construction of fused indolines from readily accessible starting materials.

Palladium-Catalyzed Tandem Cycloisomerization/Cross-Coupling of Carbonyl- and Imine-Tethered Alkylidenecyclopropanes.

Pd0 catalysts featuring phosphorus-based monodentate ligands can detour the reactivity of carbonyl-tethered alkylidenecyclopropanes (ACPs) from standard (3+2) cycloadditions towards tandem cycloisomerization/cross-coupling processes. This new reactivity lies on the formation of key π-allyl oxapalladacyclic intermediates, which are subsequently trapped with external nucleophilic partners, instead of undergoing canonical C-O reductive eliminations. Importantly, the use of imine-tethered ACP's is also feasible. Therefore, the method provides a straightforward and stereoselective entry to a wide variety of highly functionalized cyclic alcohols and amines.

[C

Pyridine-substituted alkylidenecyclopropanes (Py-ACPs) react with gold(III) salts under mild reaction conditions through an unprecedented, proximal ring-opening pathway, to generate highly appealing, catalytically active pyridine alkenyl [C^N]-gold(III) species. Mechanistic studies reveal that the activation of the C-C bond of the ACP takes place through an unusual concerted, σ-bond metathesis type-process.

The influence of proximal motor strategies on pianists' upper-limb movement variability.

Repetitive movements are considered a risk factor for developing practice-related musculoskeletal disorders. Intra-participant kinematic variability might help musicians reduce the risk of injury during repetitive tasks. No research has studied the effects of proximal motion (i.e., trunk and shoulder movement) on upper-limb movement variability in pianists. The first objective was to determine the effect of proximal movement strategies and performance tempo on both intra-participant joint angle variability of upper-limb joints and endpoint variability. The second objective was to compare joint angle variability between pianist's upper-limb joints. As secondary objectives, we assessed the relationship between intra-participant joint angle variability and task range of motion (ROM) and documented inter-participant joint angle variability. The upper body kinematics of 9 expert pianists were recorded using an optoelectronic system. Participants continuously performed two right-hand chords (lateral leap motions) while changing movements based on trunk motion (with and without) and shoulder motion (counter-clockwise, back-and-forth, and clockwise) at two tempi (slow and fast). Trunk and shoulder movement strategies collectively influenced variability at the shoulder, elbow and, to a lesser extent, the wrist. Slow tempi led to greater variability at wrist and elbow flexion/extension compared to fast tempi. Endpoint variability was influenced only along the anteroposterior axis. When the trunk was static, the shoulder had the lowest joint angle variability. When trunk motion was used, elbow and shoulder variability increased, and became comparable to wrist variability. ROM was correlated with intra-participant joint angle variability, suggesting that increased task ROM might result in increased movement variability during practice. Inter-participant variability was approximately six times greater than intra-participant variability. Pianists should consider incorporating trunk motion and a variety of shoulder movements as performance strategies while performing leap motions at the piano, as they might reduce exposure to risks of injury.

Neuromotor variability partially explains different endurance capacities of expert pianists.

During fatiguing piano tasks, muscle fatigue develops differently between expert pianists. Differences in neuromotor strategies employed could explain a slower rate of fatigue development. The objective was to compare muscle activation and kinematic variabilities between ShortDuration (i.e., pianists with less endurance) and LongDuration groups. Results from 49 pianists showed that EMG activation variability of most shoulder and upper limbs muscles was greater for the ShortDuration group with time during two piano fatiguing tasks, namely Digital and Chord tasks. Segment acceleration variability, assessed using inertial measurement units, was also greater with time for the ShortDuration group at the right arm during the Digital task, and at the thorax and head during the Chord task. Finally, thorax lateroflexion variability increased with time for the LongDuration group (but not the ShortDuration group) during the Digital task. During the Chord task, wrist flexion variability was higher for the LongDuration group compared to the ShortDuration group. These results showed a direct effect of time on the pianists' acceleration variability and EMG activation variability. In contrast, a protective effect of fatigue development could be attributed to kinematic variability. Results also suggest a higher risk of injury among pianists in the ShortDuration group.

2-(4-Bromo-phen-yl)-N-[3-(1H-imidazol-1-yl)prop-yl]quinazolin-4-amine.

In the title compound, C(20)H(18)BrN(5), the bromo-phenyl-substituted quinazoline unit is essentially planar [maximum deviation = 0.098 (3) Å] and makes a dihedral angle of 56.04 (14)° with the imidazole ring. In the crystal, mol-ecules are associated by pairs of N-H⋯N hydrogen bonds to form inversion dimers. All the quinazoline planar systems are oriented almost perpendicular to the [110] direction, making π-π inter-actions possible between adjacent dimers [centroid-centroid distances = 3.7674 (16) and 3.7612 (17) Å]. There are also a number of C-H⋯π inter-actions present. The crystal is a nonmerohedral twin, with a minor twin fraction of 0.47.

Proximal-to-Distal Sequences of Attack and Release Movements of Expert Pianists during Pressed-Staccato Keystrokes.

The aims of this study were to i) evaluate proximal-to-distal sequencing (PDS) in pianists' attack and release movements during pressed-staccato keystrokes, and ii) investigate if trunk motion facilitates PDS of upper-limb movements. Nine expert pianists performed a series of loud pressed-staccato keystrokes. Kinematic data was recorded with a 3 D motion capture system. PDS was assessed by comparing temporal organization of peak velocities from the pelvis to the wrist. Evidence of PDS was found across the kinematic chain. Pianists' use of PDS differed mainly between scapula and shoulder movements. Trunk motion facilitated PDS by increasing anticipatory shoulder movements and by preceding shoulder-girdle attack and release movements. Implications might relate to research on performance optimization and injury prevention strategies.

Exhausting repetitive piano tasks lead to local forearm manifestation of muscle fatigue and negatively affect musical parameters.

Muscle fatigue is considered as a risk factor for developing playing-related muscular disorders among professional pianists and could affect musical performance. This study investigated in 50 pianists the effect of fatiguing repetitive piano sequences on the development of forearm muscle fatigue and on piano performance parameters. Results showed signs of myoelectric manifestation of fatigue in the 42-electromyographic bipolar electrodes positioned on the forearm to record finger and wrist flexor and extensor muscles, through a significant non-constant decrease of instantaneous median frequency during two repetitive Digital (right-hand 16-tones sequence) and Chord (right-hand chords sequence) excerpts, with extensor muscles showing greater signs of fatigue than flexor muscles. In addition, muscle fatigue negatively affected key velocity, a central feature of piano sound intensity, in both Digital and Chord excerpts, and note-events, a fundamental aspect of musicians' performance parameter, in the Chord excerpt only. This result highlights that muscle fatigue may alter differently pianists' musical performance according to the characteristics of the piece played.

Time history of upper-limb muscle activity during isolated piano keystrokes.

Playing-related musculoskeletal disorders (PRMDs) in pianists can lead to the cessation of performance-related activities. A better understanding of the impact of performance parameters on muscle activities could help improve prevention of pianists' PRMDs. The purpose of this study was to assess the effect of touch and articulation (two performance parameters) on muscle activity and to compare analysis based on scalar and time-history values. Activity of nine upper-limb muscles were recorded in 12 professional classical pianists during the performance of slow-paced isolated keystrokes using pressed and struck touch and staccato and tenuto articulation. A two-way (touch and articulation) ANOVA with repeated measures was performed on time history and single-point values of muscle activations. Pressed touch prime mover muscle was the triceps brachii while struck touch entailed progressive deactivation of anti-gravity muscles before the keystroke. Compared to tenuto articulation, staccato articulation induced a muscular burst on shoulder muscles. Our results suggest that warm-up routines aiming to prevent PRMDs should integrate different types of touch and articulation. Staccato articulation appears however to be an important risk factor of PRMDs located at the shoulder structure. Temporal analysis was a more reliable tool to interpret pianists' muscle activity during keystrokes.

Effects of Trunk Motion, Touch, and Articulation on Upper-Limb Velocities and on Joint Contribution to Endpoint Velocities During the Production of Loud Piano Tones.

Piano performance involves several levels of motor abundancy. Identification of kinematic strategies that enhance performance and reduce risks of practice-related musculoskeletal disorders (PRMD) represents an important research topic since more than half of professional pianists might suffer from PRMD during their career. Studies in biomechanics have highlighted the benefits of using proximal upper-limb joints to reduce the load on distal segments by effectively creating velocity and force at the finger-key interaction. If scientific research has documented postural and expressive features of pianists' trunk motion, there is currently a lack of scientific evidence assessing the role of trunk motion in sound production and in injury prevention. We address this gap by integrating motion of the pelvis and thorax in the analysis of both upper-limb linear velocities and joint angular contribution to endpoint velocities. Specifically, this study aims to assess kinematic features of different types of touch and articulation and the impact of trunk motion on these features. Twelve pianists performed repetitive loud and slow-paced keystrokes. They were asked to vary (i) body implication (use of trunk and upper-limb motion or use of only upper-limb motion), (ii) touch (struck touch, initiating the attack with the fingertip at a certain distance from the key surface, or pressed touch, initiating the attack with the fingertip in contact with the key surface), and (iii) articulation (staccato, short finger-key contact time, or tenuto, sustained finger-key contact time). Data were collected using a 3D motion capture system and a sound recording device. Results show that body implication, touch, and articulation modified kinematic features of loud keystrokes, which exhibited not only downward but also important forward segmental velocities (particularly in pressed touch and staccato articulation). Pelvic anterior rotation had a prominent role in the production of loud tones as it effectively contributed to creating forward linear velocities at the upper limb. The reported findings have implications for the performance, teaching, and research domains since they provide evidence of how pianists' trunk motion can actively contribute to the sound production and might not only be associated with either postural or expressive features.