A regioselective base-mediated cyclization of mono-N-acylpropargylguanidines is reported. A related Ag(I)-catalyzed hydroamination strategy was recently employed to yield N3-Cbz-protected ene-guanidines, which found utility in the synthesis of naamidine A. Herein, we report the base-catalyzed hydroamination of mono-N-acylpropargylguanidines, which proceeds with the opposite regiochemistry to deliver isomerized N2-acyl-2-aminoimidazoles with broad substrate scope, circumventing the problematic regiospecific acylation of free 2-aminoimidazoles.

1will be open for general user access. TOPAZ will be a time-of-flight Laue diffractometer using a polychromatic incident beam to collect a full data set of Bragg peaks in a matter of tens of minutes rather than hours. The instrument will be optimized for high through-put small molecule crystallography of moderately sized and complex unit cells (up to around (50 Å) 3 ). To achieve this goal, custom designed focusing optics are employed for incident beam transport to the sample. Highly pixilated Anger detectors have been developed, and a novel sample positioning and loading scheme will be presented. The combination of innovative development in all areas of the instrument will enable TOPAZ to measure data from standard X-ray size crystals with an order of magnitude decrease in measurement time compared to current instruments. Various sample environments will be available including cryogenic cooling, heating, and magnetic fields. The magnetic field environment coupled with the planned polarized neutron option will allow for future experiments investigating magnetic structure and phase transitions in materials. This research is supported by UT Battelle, LLC under The KOALA instrument is a single-crystal Laue diffractometer optimised for small molecule structural studies and based on a cylindrical image-plate detector. Compared to monochromatic instruments, much smaller samples (0.1 -1 mm) can be used due to the high beam flux and the large coverage of the detector. The instrument is well suited to studies performed at multiple temperatures. The typical sample environment is a CCR with a hotstage that provides sample temperatures from 4 to 800K. Electricfield and gas charging/discharging experiments are also possible, and a high-pressure capability will be available in the near future. The KOALA instrument has been installed and awaits the scheduled restart in May 2008 of OPAL, the new Australian research reactor. Commissioning will extend over a three month period from the reactor startup. Early results from the instrument will be presented. In particular, a comparison will be made between KOALA and the VIVALDI instrument at the ILL, on which KOALA was based. Access to KOALA is typically via a 6-monthly peer review of proposals. No access charges are made for non-proprietary research. International users are encouraged to apply. The majority of all single crystal diffraction data is collected using monochromatic sources as this eases the step from measured intensities to corrected intensities. Synchrotrons have continuously pushed the limit for what can be considered a single crystal, recently a nano-porous crystal of a few micron was investigated using a microfocused X-ray beam of 1 mu m.[1] The advances in X-ray single crystal diffraction at synchrotrons have been aided by the abundant flux and improvements of optical elements. Reactor based neutron sources have only seen minor improvements in flux compared to synchrotrons and the nature of the neutrons makes it difficult to construct optical devices. However,...

The intramolecular hydroamination of a guanidine on an eneyne unit affords a guanidine-substituted diene capable of reacting with dienophiles. These substrates undergo [4+2]-cycloaddition reactions to generate a series of complex cyclic- and spirocyclic-guanidines. Select substrates can further undergo a ring opening-elimination cascade that ultimately reveals a vinyl-2-aminoimidazole. As such this cascade reaction may find application in the synthesis of oroidin-type natural products and their analogues

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