Synthesis of Tetrasubstituted Enamines Using Secondary Amines and In Situ-Generated Allenes from Nitrocyclopropanes.

A novel reaction of cyclic and acyclic secondary amines with in situ-generated allene intermediate species from nitro-substituted donor-acceptor cyclopropanes is reported. In the presence of a simple inorganic base, NaOH, tetrasubstituted enamine derivatives can be obtained in moderate to excellent yields. The reaction is operationally easy, features mild reaction conditions and simple inorganic bases, and is free of transition metals.

generation of highly reactive allenes from nitrocyclopropanes: controllable synthesis of enynes and enesters.

A new and efficient strategy for ring-opening reactions of nitrocyclopropanes is developed for the first time for the divergent synthesis of enynes and enesters via in situ generated highly reactive electron-deficient intermediate allenes. Controllable approaches resulted in enynes and enesters with up to 89% and 90% yields, respectively. The reaction features easy operation, involves green solvents and simple inorganic bases, and is transition-metal free.

Spectral phase effects and control requirements of coherent beam combining for ultrashort ultrahigh intensity laser systems.

Based on the premise that further improvements to the size and damage threshold of large-aperture optical components are severely limited, coherent beam combining (CBC) is a promising way to scale up the available peak power of pulses for ultrashort ultrahigh intensity laser systems. Spectral phase effects are important issues and have a significant impact on the performance of CBC. In this work, we analyze systematically factors such as spectral dispersions and longitudinal chromatism, and get the general spectral phase control requirements of CBC for ultrashort ultrahigh intensity laser systems.

Investigation of phase effects of coherent beam combining for large-aperture ultrashort ultrahigh intensity laser systems.

Large-aperture ultrashort ultrahigh intensity laser systems are able to achieve unprecedented super-high peak power. However, output power from a single laser channel is not high enough for some important applications and it is difficult to improve output power from a single laser channel significantly in the near future. Coherent beam combining is a promising method which combines many laser channels to obtain much higher peak power than a single channel.

[Elemental size distribution of airborne fine and ultrafine particulate matters in the suburb of Shanghai, China].

The elemental size distributions of airborne fine/ultrafine particulate matters in the suburb of Shanghai were studied using synchrotron X-ray fluorescence. Median mass aerodynamic diameter (MMAD), elemental correlation coefficient as well as enrichment factor (EF) of each size fraction were calculated to characterize the sources of elements in fine/ultrafine particulate matters. Ca and Ti distributed mainly in coarse particles (> 2 microm) with size independent enrichment factors between 0.