Metal-Free [5 + 1] Cycloaddition-Aromatization of Benzotriazoles and Sulfur Ylides to Construct 1,2,4-Benzotriazines.

Reported herein is a novel [5 + 1] cycloaddition-aromatization of benzotriazoles and sulfur ylides to efficiently construct 1,2,4-benzotriazine derivates with good yield. This new protocol does not employ any transition metal reagent and enables the cycloaddition by cleavage of the N-N single bond. The use of inexpensive and readily available starting materials, a broad substrate scope, mild reaction conditions, metal-free, and versatile functionalization of the 1,2,4-benzotriazines make this strategy more attractive.

Synthesis of Furo[2,3-e][1,4]diazepin-3-one Derivatives through Tandem Cyclization/[4 + 3] Annulation Reactions.

A variety of furo[2,3-e][1,4]diazepin-3-one derivatives were facilely synthesized through one-pot tandem cyclization/[4 + 3] annulation reactions between enynamides and α-bromohydroxamates. The reactions proceeded efficiently at room temperature, and various functional groups were well tolerated. The obtained furo[2,3-e][1,4]diazepin-3(2H)-ones containing a 7-membered dinitrogen-fused ring might be of biological and medicinal value. The products could be further derived using convenient procedures.

Spatial and temporal characteristics of tropical nights in Seoul.

We examined the spatial and temporal characteristics of tropical nights (TNs) in Seoul to determine whether land use factors increase the frequency of TN. The number of TN was derived using data from 23 Automatic Weathering Stations (AWS) in Seoul for 1998-2006, and 26 AWS in Seoul and nine Gangnam-gu stations for 2007-2013. The results show that the number of TN recorded in the Seoul Automatic Synoptic Observation System (ASOS) gradually increased from 1971 to 2013. TN occurred most frequently in early August, followed by mid-August, late July, late August, mid-July, early July, early September, and mid-September. The largest annual average difference occurred between Gangnam Station and Yeomgokdong, in spite of the short physical distance (4.5 km) between two stations at Gangnam-gu. There were more TNs at high-rise buildings and commercial business district (CBD) areas with low sky view factors (SVF) than in mountain foothill areas.

Umpolung Strategy for the Synthesis of Chiral Dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles.

Based on a novel umpolung strategy, an efficient and highly enantioselective cascade aldol/cyclization/tautomerization of the 2-(2-oxoindolin-3-yl)malononitrile to active carbonyl compounds with excellent diastereo- and enantioselectivity has been developed. Also, various enantio-enriched multifunctional dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles with adjacent spiro-stereocenters were conveniently obtained by this novel methodology. Also, the dispiro[2-amino-4,5-dihydrofuran-3-carbonitrile]bisoxindoles were easily transformed into structurally complex molecules without any effect on the diastereo- and enantioselectivity.

Comparison of the life-history parameters and competition outcome with Moina macrocopa between two morphs of Brachionus forficula.

In rotifers, the costs of morphological defenses, especially the development of long spines, have been investigated for several decades. However, the obtained results were inconsistent and the underlying reasons were complicated. Investigations on more species might be helpful to find out the reasons. In the present study, Brachionus forficula was selected as the model organism. The differences in developmental durations, life-table demography, starvation resistant time and the competitive ability with Moina macrocopa were compared between B. forficula with long (LPS) and short (SPS) posterior spines. The results showed that LPS showed relatively longer durations of juvenile stage at 1.0 × 106, 2.0 × 106 and 4.0 × 106 cells/ml Scenedesmus obliquus, and longer embryo stage at 2.0 × 106 cells/ml S. obliquus than SPS. The intrinsic rate of population increase and net reproduction rate were lower in LPS than SPS, suggesting the energy input to reproduction decreased. The starvation resistant time was also reduced in LPS, in comparison to SPS, further supporting that LPS consumed more energy, which might be directed to the development of long spines. All these results revealed that LPS spent more energy for individual growth than SPS, which might be used to develop long spines. Moreover, the maximum population density and population growth rate of LPS were always lower than those of SPS, suggesting that LPS might have a weaker competition ability with M. macrocope than SPS.

Investigation of drought-vulnerable regions in North Korea using remote sensing and cloud computing climate data.

Drought is one of the most severe natural disasters in the world and leads to serious challenges that affect both the natural environment and human societies. North Korea (NK) has frequently suffered from severe and prolonged droughts since the second half of the twentieth century. These droughts affect the growing conditions of agricultural crops, which have led to food shortages in NK. However, it is not easy to obtain ground data because NK is one of the most closed-off societies in the world. In this situation, remote sensing (RS) techniques and cloud computing climate data (CCCD) can be used for drought monitoring in NK. RS-derived drought indices and CCCD were used to determine the drought-vulnerable regions in the spring season in NK. After the results were compared and discussed, the following conclusions were derived: (1) 10.0% of the total area of NK is estimated to be a drought-vulnerable region. The most susceptible regions to drought appear in the eastern and western coastal regions, far from BaekDu-DaeGan (BDDG), while fewer drought regions are found near BDDG and the Nahngrim Mountains. The drought-vulnerable regions are the coastal regions of South Hamgyong Province, North Hamgyong Province, South Pyongan Province, and South Hwanghae Province. The latter region is the food basket of NK. (2) In terms of land cover, the drought-vulnerable regions mainly consisted of croplands and mixed forest.