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The shaping of matter into desired nanometric structures with on-demand functionalities can enhance the miniaturization of devices in nanotechnology. Herein, strong light–matter interaction was used as an optical lithographic tool to tailor two-dimensional (2D) matter into nanoscale architectures. We transformed 2D black phosphorus (BP) into ultrafine, well-defined, beyond-diffraction-limit nanostructures of ten times smaller size and a hundred times smaller spacing than the incident, femtosecond-pulsed light wavelength. Consequently, nanoribbons and nanocubes/cuboids scaling tens of nanometers were formed by the structured ablation along the extremely confined periodic light fields originating from modulation instability, the tailoring process of which was visualized in real time via light-coupled in situ transmission electron microscopy. The current findings on the controllable nanoscale shaping of BP will enable exotic physical phenomena and further advance the optical lithographic techniques for 2D materials.

A new benzodithiophene (BDT)-based building block, 3-FBDT, was synthesized and incorporated into PBDB-T-2F to yield an eco-friendly (non-aromatic and non-halogenated) solvent-processible photovoltaic copolymer, PBDB-T-2F(3/4).

Social exchange theory suggests that team members are willing to share their knowledge with each other due to the reciprocity motive stimulated by high-quality exchange relationships with their lea...

Water molecules in the immediate vicinity of biomacromolecules and biomimetic organized assemblies often exhibit a markedly distinct behavior from that of their bulk counterparts. The overall sluggish behavior of biological water substantially affects the stability and integrity of biomolecules, as well as the successful execution of various crucial water-mediated biochemical phenomena. In this Minireview, insights are provided into the features of truncated hydrogen-bond networks that grant biological water its unique characteristics. In particular, experimental results and theoretical investigations, based on chemical kinetics, are presented that have shed light on the dynamics and energetics governing such characteristics. It is emphasized how such details help us to understand the energetics of biological water, an aspect relatively less explored than its dynamics. For instance, when biological water at hydrophilic or charged protein surfaces was explored, the free energy of H-bond breakage was found to be of the order of 0.4 kcal mol-1 higher than that of bulk water.

Here, we propose an experimental methodology based on femtosecond-resolved fluorescence spectroscopy to measure the hydrogen (H)-bond free energy of water at protein surfaces under isothermal conditions. A demonstration was conducted by installing a non-canonical isostere of tryptophan (7-azatryptophan) at the surface of a coiled-coil protein to exploit the photoinduced proton transfer of its chromophoric moiety, 7-azaindole. The H-bond free energy of this biological water was evaluated by comparing the rates of proton transfer, sensitive to the hydration environment, at the protein surface and in bulk water, and it was found to be higher than that of bulk water by 0.4 kcal mol-1 . The free-energy difference is dominated by the entropic cost in the H-bond network among water molecules at the hydrophilic and charged protein surface. Our study opens a door to accessing the energetics and dynamics of local biological water to give insight into its roles in protein structure and function.

Semiconductor hybrid structures containing multiple components have been considered an ideal photocatalyst design to generate long-lived charge-separated states. Particularly for the reactions requiring high activation energies, such as a CO2 reduction reaction (CO2RR), the reaction activity is highly susceptible to the catalyst component and morphology. In this study, we selected g-C3N4 and Cu2O as photocatalytic components having bandgaps suitable for CO2RR. Then, we tried to form good electric junctions between two domains by direct growth of Cu on g-C3N4 using a polyol process. The resulting g-C3N4/Cu2O hybrid was employed as photocatalysts in an aqueous medium without hole acceptors. The catalyst exhibited a noticeable activity (5.4 mmol gcat-1h-1) and quantum yield (3.7%) with a nearly quantitative selectivity for CH4 production, superior to any other photocatalysts for CO2RR. The strong coordination of g-C3N4 to the Cu2O surface could form a conductive junction and induce effective electron transfer enforcing the Z-scheme process for CO2RR in high activity and selectivity. This result ensured the importance of junctions and interfaces in the hybrid catalyst structure to exhibit excellent photocatalytic CO2RR performances.

By taking advantage of bulk-heterojunction structures formed by blending conjugated donor polymers and non-fullerene acceptors, organic photovoltaic devices have recently attained promising power conversion efficiencies of above 18%. For optimizing organic photovoltaic devices, it is essential to understand the elementary processes that constitute light harvesters. Utilising femtosecond-resolved spectroscopic techniques that can access the timescales of locally excited (LE) state and charge-transfer (CT)/-separated (CS) states, herein we explored their photophysics in single chains of the top-notch performance donor-acceptor polymer, PM6, which has been widely used as a donor in state-of-the-art non-fullerene organic photovoltaic devices, in a single LE state per chain regime. Our observations revealed the ultrafast formation of a CT state and its equilibrium with the parent LE state. From the chain-length dependence of their lifetimes, the equilibrated states were found to idle until they reach a chain folding. At the chain folding, the CT state transforms into an interchain CT state that bifurcates into forming a CS state or annihilation within a picosecond. The observation of prevalent nonexponential behaviour in the relaxation of the transient species is attributed to the wide chain-length distribution that determines the emergence of the chain foldings in a single chain, thus, the lifetime of a LE and equilibrated CT states. Our findings indicate that the abundance of chain folding, where the generation of the "reactive" CS state is initiated from the interchain CT state, is essential for maximising charge carriers in organic photovoltaic devices based on PM6.

Two new Y6 derivatives of symmetrical YBO-2O and asymmetrical YBO-FO nonfullerene acceptors (NFAs) are prepared with a simplified synthetic procedure by incorporating octyl and fluorine substituents onto the terminal 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (INCN) moiety. By moving the alkyl substituents on the Y6 core to the terminal INCN moiety, the lowest unoccupied molecular orbital of the YBO NFAs increases without decreasing solubility, resulting in high open-circuit voltages of the devices. Molecular dynamics simulation shows that YBO-2O/-FO preferentially form core-core and terminal-terminal dimeric interactions, demonstrating their tighter packing structure and higher electron mobility than Y6, which is consistent with 2D grazing incidence X-ray scattering and space charge limited current measurements. In blend films, the hole transfer (HT) from YBO-2O/-FO to the polymer donor PM6 is studied in detail by transient absorption spectroscopy, demonstrating efficient HT from YBO-FO to PM6 with their suitable energy level alignment. Despite the simplified synthesis, YBO-FO demonstrates photovoltaic performance similar to that of Y6, exhibiting a power conversion efficiency of 15.01%. Overall, this design strategy not only simplifies the synthetic procedures but also adjusts the electrical properties by modifying the intermolecular packing and energy level alignment, suggesting a novel simplified molecular design of Y6 derivatives.

Two kinds of dumbbell-shaped acceptor-donor-acceptor (A-D-A)-type triad single-component (SC) photovoltaic molecules based on a benzodithiophene-rhodanine (BDTRh) core and [6,6]-phenyl-C61 butyric acid (PC61BA) termini, BDTRh-C2-PC61BA and BDTRh-C10-PC61BA, were synthesized by modulating the alkyl (C2 and C10) spacer lengths. Both SC photovoltaic structures had similar UV-vis spectra in solution, but BDTRh-C10-PC61BA showed a significantly higher absorption coefficient as a thin film. In films, a more facile intermolecular photo-induced charge transfer was observed for BDTRh-C10-PC61BA in the broad-band transient absorption measurements. BDTRh-C10-PC61BA also exhibited a higher hole mobility (by 25 times) and less bimolecular recombination than BDTRh-C2-PC61BA. By plotting the normalized external quantum efficiency data, a higher charge-transfer state was measured for BDTRh-C10-PC61BA, reducing its voltage loss. A higher power conversion efficiency of ∼2% was obtained for BDTRh-C10-PC61BA, showing higher open-circuit voltage, short-circuit current density, and fill factor than those of BDTRh-C2-PC61BA devices. The different carrier dynamics, voltage loss, and optical and photoelectrical characteristics depending on the spacer length were interpreted in terms of the film morphology. The longer decyl spacer in BDTRh-C10-PC61BA afforded a significantly enhanced intermolecular ordering of the p-type core compared to BDTRh-C2-PC61BA, suggesting that the alkyl spacer length plays a critical role in controlling the intermolecular packing interaction.

This paper describes the manufacturing study of ITER Lower Cryostat Thermal Shield (LCTS) cylinder components, which are to be delivered to ITER site. All LCTS cylinder 20 ° sectors will be assembled at the ITER site by the flange joints, which are welded to the shells. Reliability of cooling pipe welding was checked by two inspection methods: endoscopy and vacuum leak test. Pre-assembly of three 20 ° sectors is one of the important step to ensure dimensional tolerance and its process is described in details. Dimensions of the pre-assembled 60 ° sector was measured by a laser tracker. The qualification of silver coating facility was carried out using a simple well-defined plate mock-up. After the facility qualification, silver coating of LCTS cylinder 20 ° sectors had been conducted. Technical efforts to improve the coated surface quality are presented in this paper.

PurposeThe purpose of this paper is to explore the dual effects of task conflict on team creativity and the role of team-focused transformational leadership (TFL) as a key contingency in the task conflict–team creativity relationship.Design/methodology/approachData were collected from 325 teams across ten large companies in South Korea. The study tested the hypothesized moderated mediation model using an SPSS macro (PROCESS, Hayes, 2008).FindingsResults showed that task conflict is directly and positively related to team creativity and is negatively and indirectly related to team creativity via relationship conflict. Furthermore, the study found that team-focused TFL moderates all paths through which task conflict affects team creativity. Specifically, team-focused TFL enhances the positive direct effect of task conflict and alleviates the negative indirect effects of task conflict on team creativity.Research limitations/implicationsAlthough this study could not test the causal chains of the proposed relationships owing to a cross-sectional nature of data, the present research provides theoretical implications for the conflict, leadership and team creativity literatures. The study highlights the role of transformational leadership in the process through which team conflict is managed so as to increase team creativity.Practical implicationsTo capitalize on the creativity-related benefits associated with task conflict, managers will need to pay attention to the role they can play and their leadership that emphasizes collective goals and identity. Managers and team leaders are also expected to intervene in conflict situations to minimize the harmful effect of task conflict that may take place owing to the association between task conflict and relationship conflict.Social implicationsThe findings will have implications for any social contexts where people work together toward common goals. In such contexts, the study emphasizes the role of leadership in teams to use the creative potential associated with different opinions and values regarding what and how work to be completed.Originality/valueThe study’s examination of the dual paths through which task conflict affects team creativity brings insights into why the impact of task conflict on team creativity has been inconsistent or unclear in past research. This paper also articulates a leader’s role in teams in relation to managing team conflict to increase team creativity.

We examined the relationship between team task knowledge diversity and team creativity, and the moderating role of team status inequality, with a focus on organizational tenure and rank inequality. By adopting an input–process–output framework, we hypothesized that teams would achieve high levels of creativity when they have a large pool of task-relevant expertise that is differentiated and specialized among team members, but the relationship would be weakened when team members have different statuses. We tested our hypotheses using data from 325 teams of employees at 10 companies in South Korea. Results showed that task knowledge diversity was positively associated with team creativity and a team's status inequality in terms of organizational tenure moderated the relationship in a negative way. Our findings contribute to the literature on team creativity by providing new insights regarding how status inequality, which is almost ubiquitous in workplaces, plays a role in a dynamic team process for creativity.

ITER Thermal Shield (TS) reduces radiation heat loads from vacuum vessel and cryostat to superconducting magnet structure. One of the key process among the fabrication of TS is the silver electroplating to reduce the emissivity. Requirement on emissivity of TS surface after silver coating is below 0.05 at the room temperature. In practice, inevitable non-coated areas exist due to the intrinsic geometry of TS. These local defects can be repaired by attaching thin silver coated patch with spot welding. This paper treats structural characteristics on the spot welding of silver coated plates. Strength of spot welding is measured by tensile shear test. Distances between spot welding are verified by finite element analysis considering temperature deviation between TS surface and patch. Finally, thermal stress analysis for the several applications to TS main components are presented.

Research has generally supported a linear positive relationship between team efficacy and team performance. More recent theories and research suggest, however, that teams can become overly efficacious and team efficacy may exhibit nonlinear relationships with outcomes. The current study investigates the possibility that team efficacy is associated with decreases in team performance when the level of team efficacy is excessively high or low. This study further suggests that cohesion is an important contextual factor that may affect the curvilinear relationship between team efficacy and performance such that high levels of cohesion will magnify the curvilinear relationship whereas low levels of cohesion will flatten the curvilinear pattern. Hypotheses were tested using 324 employees in 34 work teams. Results demonstrate that the curvilinear relationship between team efficacy and team performance was strongest when cohesion was high; the relationship flattened when cohesion was low. Implications and limitations are discussed.

In the ITER tokamak, a thermal shield (TS) is installed to reduce the heat oad radiated to the superconducting magnet system from vacuum vessel (VV) and cryostat. TS has a thin silver surface to keep its emissivity below 0.05. The silver surface is achieved by electroplating. However, some vacuum vessel thermal shield (VVTS) may be imperfectly silver coated due to their complex geometry. When a segment of the VVTS is immersed in silver coating bath, electron is concentrated to the sharp edge of segment and doesn’t reach to the deep area. Also, solution in a segment surface for pre-treatment may not be removed in some point due to its geometry, and it disturbs the silver coating. In this paper, the impact of non-silver coating on heat loads from TS to magnet system is researched as following process; 1) Identification of area where the VVTS may be imperfectly silver coated – it is obtained from actual silver coating of ITER VVTS. 2) FE model/analysis condition construction of VVTS – VVTS solid element / cooling tube beam element is combined, and silver coated / non-coated area shell element with respective emissivity is applied. 3) Thermal analysis of VVTS with non-silver coated area – heat load via non-coated area of VVTS is calculated, and its impact to magnet system is estimated. According to thermal analysis of VVTS, the essential silver coating points to reduce heat load are identified. As remedial action is applied to the essential points, the heat load from VVTS to magnet system is minimized.

The role of the ITER thermal shield (TS) is to minimize the radiation heat load transferred from the warm components to the superconducting magnet operating at 4.5 K. Fabrication of the TS components is ongoing. Manufacturing of LCTS (Lower Cryostat TS) cylinder and VVTS (Vacuum Vessel TS) sector #6 was completed. The leak tightness of the cooling tubes, the on-site installation feasibility and the quality of the silver coated surfaces are main concerns during the manufacturing. Leak tightness of the cooling tubes is guaranteed by the test and the inspection. The surfaces of the cooling tube inside are inspected visually using the endoscope and the leak tightness has been qualified by the pressure and helium leak test. The on-site installation feasibilities are validated by the preassembly test at the factory. According to the qualified coating process, the TS panels are electro-plated with silver. This paper describes the manufacturing progress and the technical achievements.

The ITER thermal shield (TS) minimizes radiation heat loads from the vacuum vessel and the cryostat to the superconducting magnets. It is actively cooled by pressurized Helium gas. The TS Manifold (TSM) provides Helium coolant from the cold valve box (CVB) to the cooling tubes on the TS panels. Among the manufacturing of TSM, the most challenging issue is fabrication of pipe T-branches which is consisted of drilling, T-extrusion, surface milling and orbital welding. After the orbital welding the welded areas are tested by visual and x-ray examinations. Functional tests are carried out by cold shock and pressure and vacuum leak testing. This paper introduces the procedures for the fabrication and examinations for the T-Branch of the TSM.

(2002). The Unwilling Hosts: State, Society and the Control of Guest Workers in South Korea. Asia Pacific Business Review: Vol. 8, No. 4, pp. 67-94.

As viscous hydroxylic organic compounds, diols are of interest for their functional molecular conformation, which is based on inter- and intramolecular hydrogen (H)-bonds. By utilising steady-state electronic and vibrational spectroscopy, time-resolved fluorescence spectroscopy, and computational analyses, we report the association of the hydroxyl groups of diols via intra- or intermolecular H-bonds to enhance their reactivity as a base. Whereas the formation of an intermolecularly H-bonded dimer is requisite for diols of weak intramolecular H-bond to extract a proton from a model strong photoacid, a well-configured single diol molecule with an optimised intramolecular H-bond is revealed to serve as an effective Bronsted base with increased basicity. This observation highlights the collective role of H-bonding in acid–base reactions, and provides mechanistic backgrounds to understand the reactivity of polyols in the acid-catalysed dehydration for the synthesis of cyclic ethers at the molecular level.

Summary This study describes a multilevel examination of person–group (PG) fit perceptions in a sample of 1023 individuals working in 92 teams at a private sector R&D firm. Using confirmatory factor analysis and multilevel random coefficient modeling, we provide evidence that perceptions of team-level collective fit are unique from aggregated individual-level PG fit perceptions at the individual and team levels. We demonstrate that collective values-based and abilities-based fit perceptions showed unique and positive relationships with team cohesion, team efficacy, and team performance, after accounting for aggregated individual perceptions of PG fit. Results also demonstrate that cohesion partially mediates the relationship between collective fit and team performance. Cross-level effects were also supported, indicating that collective fit explains additional variance in individual-level outcomes, beyond individual-level PG fit perceptions. The usefulness of employing a multilevel approach to studying PG fit is discussed. Copyright © 2014 John Wiley & Sons, Ltd.

The ITER toroidal field (TF) conductor is made up of superconducting Nb3Sn and copper strands assembled into a multistage, rope-type cable inserted into a conduit of butt-welded stainless steel jacket sections. For the ITER Project, the Korean Domestic Agency (KODA) took the responsibility of the procurement of 27 superconducting conductors for the ITER TF magnets. After concluding the Procurement Arrangement (PA) with the ITER International Organization in May 2008, KODA has been implementing the PA through four major industrial contracts: (1) Nb3Sn strand, (2) cable, (3) stainless steel jacket sections, and (4) jacketing. Prior to the production of conductors required for the TF coils, one 760-m-long copper dummy conductor and one 100-m-long superconducting conductor were fabricated for manufacturing process qualification. As of June 2013, 16 TF conductors were successfully manufactured. The full-size conductor performance tests in the SULTAN facility yielded very high performance. This article describes the technical requirements of the TF conductor and how KODA has been manufacturing the conductors with a high-level quality assurance/quality control system. It also presents the results of acceptance tests, including those of the SULTAN test.

In this study, we examined the effects of chief executive officer (CEO) characteristics and organizational systems on organizational creativity, particularly in small- and medium-sized enterprises (SMEs). Using upper echelon and contingency perspectives, we hypothesized that CEO characteristics would promote organizational creativity in SMEs, but the effect of CEO characteristics would be attenuated when SMEs have strong organizational learning systems in place. Consistent with our expectations, the results show that a CEO's orientation toward employee development plays an important role in organizational creativity. Moreover, the effect of CEO development orientation on organizational creativity is greatest when the organizational system is weak. Theoretical and practical implications are also discussed.

Diversity-oriented synthesis (DOS) can provide a collection of diverse and complex drug-like small molecules, which is critical in the development of new chemical probes for biological research of undruggable targets. However, the design and synthesis of small-molecule libraries with improved biological relevance as well as maximized molecular diversity represent a key challenge. Herein, we employ functional group-pairing strategy for the DOS of a chemical library containing privileged substructures, pyrimidodiazepine or pyrimidine moieties, as chemical navigators towards unexplored bioactive chemical space. To validate the utility of this DOS library, we identify a new small-molecule inhibitor of leucyl-tRNA synthetase–RagD protein–protein interaction, which regulates the amino acid-dependent activation of mechanistic target of rapamycin complex 1 signalling pathway. This work highlights that privileged substructure-based DOS strategy can be a powerful research tool for the construction of drug-like compounds to address challenging biological targets., Diversity-oriented synthesis is useful for generating complex molecular structures occupying diverse molecular space. Here the authors report a strategy to access libraries of privileged heterocyclic structures, and furthermore identify an inhibitor of LRS–RagD protein–protein interaction.

This article explores antecedents and outcomes of group-level person-group (PG) fit perceptions. Based on the categorization-elaboration model (CEM), the authors explain how social category (gender and age) and informational diversity (education and work experience) in work teams may elicit supplementary and complementary fit perceptions among team members. The authors then examine two mechanisms through which perceived fit might influence leader-rated group performance. Supplementary fit (similarity on values) is hypothesized to work through a relationship-oriented mechanism by influencing social cohesion. Complementary fit (abilities meet job demands) is expected to work through a task-oriented mechanism by influencing the teams’ transactive memory systems. Participants include employees (N = 1,101) and leaders (N = 116) from 116 work teams in two private firms located in Seoul, Korea. Results generally support the hypothesized relationships, with the task-oriented mechanism being more influential of group performance. Post hoc analyses also suggest that a superordinate perception of PG fit may underlie the assessments of the more specific types of fit. The authors conclude that diversity within groups influences an emergent perception of group-level fit, having related supplementary and complementary components, which in turn are associated with group-level outcomes.

This article examines two-way trust (leader's trust in subordinate and subordinate's trust in his or her leader) in the context of the leader–subordinate dyad, and the relationship between the subordinate's perception of this two-way trust and the subordinate's trust in the organization. Based on a survey with a sample of 182 Korean Air pilots, the results show that a perceived leader's trust in a subordinate is positively related to the subordinate's trust in that leader, and that a subordinate's trust in his or her leader mediates the relationship between the leader's trust in subordinate and the subordinate's trust in the organization. A summary of the contributions and implications of this research are discussed, as are suggestions for future research.

Temperature compensation circuit is implemented by using the temperature sensor, and Intermodulation (IM) Specification of Power Amplifier is satisfied in the temperature range of with this temperature compensation circuit. The output voltage of temperature compensation circuit which vary 170mV with the temperature is applied to the gate of TR in 3W output power Amplifier. As the result, right 3rd IM component is -18.5~-26dBm, left 3rd IM component is -18.5~-35dBm, and the left and right 5th IM component is -24~-26dBm in the temperature range of . It is confirmed that IM specification of power amplifier which is under -17dBm in the whole temperature range is satisfied.

(2002). The Unwilling Hosts: State, Society and the Control of Guest Workers in South Korea. Asia Pacific Business Review: Vol. 8, No. 4, pp. 67-94.

In this paper, we study the concepts of isocompactness and cl-isocompactness. We generalize a pure space defined by Arhangelskii and get some results on initially K-compact spaces. We also consider open problems related to isocompactness and cl-isocompactness.

As employees become more experienced with burnout, it is important for researchers and managers to understand the nature of the relationship between their experienced burnout, identity violation, j...

Applying social identity theory, we examine how leader’s power perceived by team members influences team members’ citizenship behaviors. We argue that leader’s power positively influences the exten...

(2001). The Corporate Culture Change Campaigns in Korea: Lessons from Their Failures. Asia Pacific Business Review: Vol. 7, No. 4, pp. 89-110.

Although a quarter of a century has passed since Janis proposed his groupthink model in 1972, there is very little consensus among researchers on the validity of the model. This study conducted a comprehensive empirical investigation of Janis's model by including all 24 variables in the research. Data were collected from 64 four-person ad hoc groups; the group discussion sessions were videotaped and content-analysed afterwards. Statistical analyses revealed that Janis's predictions about the causal relationship among four groups of variables in the model are only partially correct; when the effects of individual independent variables on the dependent variables were tested, Janis's predictions were confirmed in only two out of 23 cases. Copyright © 2000 John Wiley & Sons, Ltd.

Search for a new alpha-methylene-gamma-butyrolactone-bearing 6-substituted purine as a potential antitumor agent has led to synthesize seven, hitherto unreported, 5'-Methyl-5'-[(6-substituted-9H-purin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofurans (H, Cl, I, CH3, NH2, SH,C=O) (6a-g). These include 5'-Methyl-5'-[(9H-purin-9-yl)methyl]-2'-oxo-3'-methylenetetrahydrofur ans (6a), 5'-Methyl-5'-[(chloro-9H-purin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofurans (6b), 5'-Methyl-5'-[(6-iodo-9H-purin-9-yl) methyl]-2'-oxo-3'-methylenetetrahydrofurans (6c), 5'-Methyl-5'-[(6-methyl-9H-purin-9-yl) methyl]-2'-oxo-3'-methylenetetrahydrofurans (6d), 5'-Methyl-5'-[(9H-adenin-9-yl)methyl]-2'-oxo-3-methylenetetrahy drofurans (6e), 5'-Methyl-5'-[(6-mercapto-9H-purin-9-yl) methyl]-2'-oxo-3'-methylenetetrahydrofurans (6f) and 5'-Methyl-5'-[(9H-hypoxanthin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofurans (6g) which were made by the Reformatsky-type reaction of ethyl alpha-(bromomethyl) acrylate with the corresponding (6-substituted-9H-purin-9-yl)-2-propanone intermediates (5a-g). These ketone intermediates 5a-g, 1-(9H-purin-9-yl)-2-propanone (5a), 1-(6-chloro-9H-purin-9-yl)-2-propanone (5b), 1-(6-iodo-9H-purin-9-yl)-2-propanone (5c), 1-(6-methyl-9H-purin-9-yl)-2-propanone (5d), 1-(9H-adenin-9-yl)-2-propanone (5e), 1-(6-mercapto-9H-purin-9-yl)-2-propanone (5f), and 1-(9H-hypoxanthin-9-yl)-2-propanone (5g) were directly obtained by the alkylation of the 6-substituted purine bases with the chloroacetone in the presence of K2CO3 (or NaH) under DMF (or DMSO). The preliminary in vitro cytotoxicity assay for the synthetic alpha-methylene-gamma-butyro-lactone compounds (6a-g) were determined against three cell lines (PM-3A, P-388, and K-562) and showed the moderate antitumor activity (IC50 ranged from 1.4 to 4.3 micrograms/ml) with the compound 5'-methyl-5'-[(9H-hypoxanthin-9-yl)methyl]-2'-oxo-3'- methylenetetrahydrofuran (6g) showing the least antitumor activity.

Six, heretofore undescribed, 5′-Methyl-5′-(5-Substituted uracil-1-ylmethyl)-2′-oxo-3′-methylenetetrahydrofurans (F, Cl, Br, I, CH3, H) (6a-f) were synthesized and evaluated against three cell lines (FM-3A, P-388 and U-937). For the preparation of α-methylene-γ-butyrolactone bearing 5-substituted uracils (6a-f), the efficient Reformatsky type reaction was employed which involves the treatment of ethyl α-(bromomethyl) acrylate and zinc with the respective 5-substituted uracil-1-ylacetones (5a-f). The acetone derivatives (5a-f) were directly obtained by the respective alkylation reaction of 5-substituted uracils with chloroacetone in the presence of K2CO3 (or NaH). These lactone compounds6a-f exhibited moderate to significant activity in all of the three cell lines, and6b, 6c and6e showed significant antitumor activities (inhibitory concentrations (IC50) ranged from 1.3–3.8 μg/ml).

(1994). REGIOSELECTIVE SYNTHESIS OF 10-HYDROXY-11-METHOXYAPORPHINE FROM (RS)-10,11-DIHYDROXYAPORPHINE. Organic Preparations and Procedures International: Vol. 26, No. 4, pp. 479-482.