A novel and efficient approach for the regioselective selenylation of 4H‐pyrido‐[1,2‐a]‐pyrimidin‐4‐ones with diselenides at room temperature has been developed. This procedure is catalyzed by N‐iodosuccinimide under metal‐free conditions with a broad range of substrate scopes and affords C3 selenylation products in good to excellent yields. Furthermore, the sulfenylation with diphenyl disulfides and 4‐methylbenzenethiol in this transformation is successful.
An efficient and simple protocol for silvercatalyzed direct C3 phosphonation of 4H-pyrido[1,2-a] pyrimidin-4-ones with dialkyl phosphites has been developed. The reaction shows high regioselectivity, broad scope of substrates, and good functional group compatibility. Importantly, the phosphorylated 4H-pyrido[1,2-a]pyrimidin-4-one product 3 u can be employed as efficient probes for Fe 3 + .
Organized carbon nanotubes (CNTs) have been grown at a fast rate by a gas-phase, catalytic CVD technique at 600-750°C for 15 min with the iron pentacarbonyl/acetylene/hydrogen system. The CNT growth at various temperatures and flow rates of iron pentacarbonyl, acetylene, and hydrogen, has been quantitatively analyzed by its length. The CNT growth accelerates with growth temperatures up to 700°C, but depends upon growth conditions at 750°C. Acetylene at a higher input deactivates catalysts owing to its supersaturated carbon content, approaching that of Fe 3 C. The deactivation of catalysts can be overcome by the addition of hydrogen via a hydrocarbon reaction to refresh the poisoned catalysts or by the high input of iron pentacarbonyl to provide fresh catalysts for the continuous CNT growth. CNTs with a longest tube length of 845±28 lm and a fastest growth rate of 56±1.9 lm min -1 were obtained. A mixed-mode growth mechanism combining the tip-and basegrowth modes was suggested.
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