Distal radical migration strategy: an emerging synthetic means

2018 ◽  
Vol 47 (3) ◽  
pp. 654-667 ◽  
Author(s):  
Weipeng Li ◽  
Wentao Xu ◽  
Jin Xie ◽  
Shouyun Yu ◽  
Chengjian Zhu
Keyword(s):  
Rapid Development ◽  
Long Distance ◽  
Migration Strategy ◽  
Bond Functionalization ◽  
The Past ◽  
Radical Migration

In the past three years, we have witnessed the rapid development of C–C and C–H bond functionalization by means of long-distance radical migration events which bring us a new platform to deal with the challenging C–C and C–H bond functionalization.

scholarly journals Recent Advances in C–H Bond Functionalization with Ruthenium-Based Catalysts

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 173 ◽  
Author(s):  
Keisham Singh
Keyword(s):  
Transition Metals ◽  
Bond Cleavage ◽  
Rapid Development ◽  
Bond Functionalization ◽  
Bond Forming ◽  
The Past ◽  
Tremendous Progress ◽  
Specific Manner ◽  
Ruthenium Catalysis ◽  
Cleavage Reactions

The past decades have witnessed rapid development in organic synthesis via catalysis, particularly the reactions through C–H bond functionalization. Transition metals such as Pd, Rh and Ru constitute a crucial catalyst in these C–H bond functionalization reactions. This process is highly attractive not only because it saves reaction time and reduces waste,but also, more importantly, it allows the reaction to be performed in a highly region specific manner. Indeed, several organic compounds could be readily accessed via C–H bond functionalization with transition metals. In the recent past, tremendous progress has been made on C–H bond functionalization via ruthenium catalysis, including less expensive but more stable ruthenium(II) catalysts. The ruthenium-catalysed C–H bond functionalization, viz. arylation, alkenylation, annulation, oxygenation, and halogenation involving C–C, C–O, C–N, and C–X bond forming reactions, has been described and presented in numerous reviews. This review discusses the recent development of C–H bond functionalization with various ruthenium-based catalysts. The first section of the review presents arylation reactions covering arylation directed by N–Heteroaryl groups, oxidative arylation, dehydrative arylation and arylation involving decarboxylative and sp3-C–H bond functionalization. Subsequently, the ruthenium-catalysed alkenylation, alkylation, allylation including oxidative alkenylation and meta-selective C–H bond alkylation has been presented. Finally, the oxidative annulation of various arenes with alkynes involving C–H/O–H or C–H/N–H bond cleavage reactions has been discussed.

History—an overview

2018 ◽  
Author(s):  
Oriol Bohigas ◽  
Hans A. Weidenmüller
Keyword(s):  
Random Matrix Theory ◽  
Random Matrix ◽  
Matrix Theory ◽  
Rapid Development ◽  
The Past ◽  
History Of ◽  
And Mathematics

An overview of the history of random matrix theory (RMT) is provided in this chapter. Starting from its inception, the authors sketch the history of RMT until about 1990, focusing their attention on the first four decades of RMT. Later developments are partially covered. In the past 20 years RMT has experienced rapid development and has expanded into a number of areas of physics and mathematics.

COMBINING ORAL TRADITIONS AND BAYESIAN CHRONOLOGICAL MODELING TO UNDERSTAND VILLAGE DEVELOPMENT IN THE GULF OF PAPUA (PAPUA NEW GUINEA)

Radiocarbon ◽  
2021 ◽  
pp. 1-21
Author(s):  
Chris Urwin ◽  
Quan Hua ◽  
Henry Arifeae
Keyword(s):  
Papua New Guinea ◽  
New Guinea ◽  
Oral Traditions ◽  
Long Distance ◽  
Spatial History ◽  
The Past ◽  
History Of ◽  
Gulf Of Papua ◽  
The Village

ABSTRACT When European colonists arrived in the late 19th century, large villages dotted the coastline of the Gulf of Papua (southern Papua New Guinea). These central places sustained long-distance exchange and decade-spanning ceremonial cycles. Besides ethnohistoric records, little is known of the villages’ antiquity, spatiality, or development. Here we combine oral traditional and 14C chronological evidence to investigate the spatial history of two ancestral village sites in Orokolo Bay: Popo and Mirimua Mapoe. A Bayesian model composed of 35 14C assays from seven excavations, alongside the oral traditional accounts, demonstrates that people lived at Popo from 765–575 cal BP until 220–40 cal BP, at which time they moved southwards to Mirimua Mapoe. The village of Popo spanned ca. 34 ha and was composed of various estates, each occupied by a different tribe. Through time, the inhabitants of Popo transformed (e.g., expanded, contracted, and shifted) the village to manage social and ceremonial priorities, long-distance exchange opportunities and changing marine environments. Ours is a crucial case study of how oral traditional ways of understanding the past interrelate with the information generated by Bayesian 14C analyses. We conclude by reflecting on the limitations, strengths, and uncertainties inherent to these forms of chronological knowledge.

Organophotoredox-Catalyzed C–H Alkylation of Imidazoheterocycles with Malonates: Total Synthesis of Zolpidem

Synthesis ◽  
2020 ◽  
Author(s):  
Narendra R. Chaubey ◽  
Anant R. Kapdi ◽  
Biswanath Maity
Keyword(s):  
Total Synthesis ◽  
Room Temperature ◽  
Drug Molecule ◽  
Bond Functionalization ◽  
First Report ◽  
Mild Conditions ◽  
The Past ◽  
Hypnotic Drug ◽  
Free Environment

AbstractOrganophotocatalytic C–H bond functionalization has attracted a lot of attention in the past several years due to the possibility of catalyzing reactions in a metal- and peroxide-free environment. Continuing on these lines, an organophotoredox-catalyzed C–H functionalization of imidazo[1,2-a]pyridines and related heterocycles with bromomalonates under mild conditions is reported, providing excellent yields of the products at room temperature. This is the first report involving malonates as coupling partners leading to the synthesis of a range of functionalized products including total synthesis of zolpidem, a sedative­-hypnotic drug molecule.

scholarly journals International Schools for Young Astronomers (ISYA): a programme of the International Astronomical Union

2006 ◽  
Vol 2 (SPS5) ◽  
pp. 221-228 ◽  
Author(s):  
Michèle Gerbaldi
Keyword(s):  
International Schools ◽  
Rapid Development ◽  
Data Access ◽  
International Astronomical Union ◽  
Information And Communications Technologies ◽  
The Past ◽  
Data Archives ◽  
International Astronomical ◽  
Communications Technologies

AbstractThis paper outlines the main features of the International Schools for Young Astronomers (ISYA), a programme developed by the International Astronomical Union (IAU) in 1967. The main goal of this programme is to support astronomy in developing countries by organizing a school lasting 3 weeks for students with typically a M.Sc. degree. The context in which the ISYA were developed has changed drastically over the past 10 years. We have moved from a time when access to any large telescope was difficult and mainly organized on a national basis, to the situation nowadays where data archives are established at the same time that any major telescope, ground-based or in space, is built, and these archives are accessible from everywhere. The concept of the virtual observatory reinforces this access. However, the rapid development of information and communications technologies and the increasing penetration of internet have not yet removed all barriers to data access. The role of the ISYA is addressed in this context.

scholarly journals Great flights by great snipes: long and fast non-stop migration over benign habitats

2011 ◽  
Vol 7 (6) ◽  
pp. 833-835 ◽  
Author(s):  
Raymond H. G. Klaassen ◽  
Thomas Alerstam ◽  
Peter Carlsson ◽  
James W. Fox ◽  
Åke Lindström
Keyword(s):  
Migratory Birds ◽  
Strenuous Exercise ◽  
Migration Route ◽  
Long Distance ◽  
Migration Strategy ◽  
Ice Caps ◽  
Fuel Loads ◽  
Stopover Sites ◽  
Ecological Barriers ◽  
Suitable Habitats

Migratory land birds perform extreme endurance flights when crossing ecological barriers, such as deserts, oceans and ice-caps. When travelling over benign areas, birds are expected to migrate by shorter flight steps, since carrying the heavy fuel loads needed for long non-stop flights comes at considerable cost. Here, we show that great snipes Gallinago media made long and fast non-stop flights (4300–6800 km in 48–96 h), not only over deserts and seas but also over wide areas of suitable habitats, which represents a previously unknown migration strategy among land birds. Furthermore, the great snipes achieved very high ground speeds (15–27 m s −1 ), which was not an effect of strong tailwind support, and we know of no other animal that travels this rapidly over such a long distance. Our results demonstrate that some migratory birds are prepared to accept extreme costs of strenuous exercise and large fuel loads, even when stopover sites are available along the route and there is little tailwind assistance. A strategy of storing a lot of energy before departure, even if migration is over benign habitats, may be advantageous owing to differential conditions of fuel deposition, predation or infection risk along the migration route.

Chinese Business Practice in the Late Imperial Period

2013 ◽  
Vol 14 (4) ◽  
pp. 769-793 ◽  
Author(s):  
Madeleine Zelin
Keyword(s):  
Rapid Development ◽  
Chinese Economy ◽  
Long Distance ◽  
Late Imperial ◽  
Market Expansion ◽  
Chinese Business ◽  
Everyday Practices ◽  
Imperial Period ◽  
Business In China ◽  
The Impact

The rapid development of the Chinese economy over the past several decades has stimulated new interest in the institutions, practices, and social formations that supported the development of business in China before the intensification of pressure from Western traders to conform to “modern” practices in the late nineteenth and early twentieth centuries. This article aims to provide a foundation for understanding merchant practice as it developed during the important years of market expansion during the last Chinese dynasty and to dispel some of the enduring myths about the Chinese merchant, his relationship to family, community, and the state, and the ideological constraints on his activities. To that end I examine several aspects of late imperial merchant culture, beginning with the everyday practices that allowed business to flourish in the Qing, turning next to the large social formations through which long-distance merchants in particular identified and pursued their interests, and ending with some preliminary thoughts on the impact of the laissez-faire policies of the last dynasty and their implications for post-Imperial China.

Chihuahuan Archaeology

2017 ◽  
Author(s):  
Michael E. Whalen ◽  
Paul E. Minnis
Keyword(s):  
Rapid Development ◽  
Colonial Period ◽  
Complex Societies ◽  
Casas Grandes ◽  
Culture Area ◽  
The Past ◽  
Single Culture ◽  
International Boundary ◽  
Sedentary Life ◽  
The U.S

Northwestern Chihuahua, Mexico, and the U.S. Southwest share broadly similar pre-colonial cultures and sequences of change. In fact, the present-day international boundary artificially divides a single culture area. Even so, northwestern Chihuahua is not simply a southern extension of the U.S. Southwest. This chapter reviews the past of northwestern Chihuahua from the early pre-ceramic era through late pre-Hispanic times, showing how these cultures were similar to and different from their counterparts in the Southwest. It is clear that maize farming and at least semi-sedentary life were introduced early in Chihuahua, and this formed a basis for the rapid development of subsequent cultures. The apogee of the area’s late pre-colonial period is the famous center of Paquimé (or Casas Grandes). It is widely recognized as one of the most complex societies of the pre-Hispanic Pueblo world.

scholarly journals Adverse Selection in P2P Lending: Does Peer Screening Work Efficiently?—Empirical Evidence from a P2P Platform

2021 ◽  
Vol 9 (4) ◽  
pp. 73
Author(s):  
Yao Wang ◽  
Zdenek Drabek
Keyword(s):  
Adverse Selection ◽  
Rapid Development ◽  
Financial System ◽  
Decision Making Process ◽  
Type Ii Error ◽  
Close Attention ◽  
Large Dataset ◽  
The Past ◽  
P2p Lending ◽  
Online Lending

The rapid development of online lending in the past decade, while providing convenience and efficiency, also generates large hidden credit risk for the financial system. Will removing financial intermediaries really provide more efficiency to the lending market? This paper used a large dataset with 251,887 loan listings from a pioneer P2P lending platform to investigate the efficiency of the credit-screening mechanism on the P2P lending platform. Our results showed the existence of a TYPE II error in the investors’ decision-making process, which indicated that the investors were predisposed to making inaccurate diagnoses of signals, and gravitated to borrowers with low creditworthiness while inadvertently screening out their counterparts with high creditworthiness. Due to the growing size of the fintech industry, this may pose a systematic risk to the financial system, necessitating regulators’ close attention. Since, investors can better diagnose soft signals, an effective and transparent enlargement of socially related soft information together with a comprehensive and independent credit bureau could mitigate adverse selection in a disintermediation environment.

scholarly journals Advanced Thermally Drawn Multimaterial Fibers: Structure-Enabled Functionalities

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zhe Wang ◽  
Mengxiao Chen ◽  
Yu Zheng ◽  
Jing Zhang ◽  
Zhixun Wang ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Early Stage ◽  
Rapid Development ◽  
Wearable Devices ◽  
Surface Structures ◽  
The Past ◽  
High Scalability ◽  
Drawing Technique ◽  
Symmetric Structures ◽  
Thermal Drawing

Thermally drawn multimaterial fibers have experienced rapid development in the past two decades owing to the high scalability, uniformity, and material and structure compatibility of the thermal drawing technique. This article reviews various multimaterial fibers based on different functional structures and their applications in disparate fields. We start from the functional structures achieved in optical fibers developed in the early stage of thermally drawn fibers. Subsequently, we introduce both typical functional structures and unique structures created in multimaterial fibers for varying applications. Next, we present the early attempts in breaking the axial symmetric structures of thermally drawn fibers for extended functionalities. Additionally, we summarize the current progress on creating surface structures on thermally drawn fibers. Finally, we provide an outlook for this trending topic towards wearable devices and smart textiles.

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