Solid supports microtubes

Recently, Raju et al.6 reported an attractive method for the preparation of unsymmetrical ureas on solid-phase resins, employing nitrophenylcarbamates as the key intermediates. They used this method to synthesize ureas derived from simple amines. Here, we report that unsymmetrical ureas can be formed in high yield and purity using MicroTubes as the solid supports. 

Another kind of solid support that has gained more popularity is the surface-modified polypropylene, such as the Multipin crown and Microtubes. Reaction 3 was carried out on lightly and highly cross-linked polystyrene resins (1 % and >20% divinylbenzene, respectively), poly sty rene-PEG resin, and a surface-functionalized Microtube reactor.12 The reaction kinetics on these supports is compared in Figures 7.4 and 7.5. The reaction on the highly cross-linked polystyrene resin was shown to be slower than on other supports and the reaction on Microtube was faster than on polystyrene resins. 

Microreactors containing a solid-supported organic catalyst have also been developed. For example, solid-supported l,5,7-triazabicyclo-[4.4.0] undec-3-ene is introduced to a microtube reactor (Figure 7.26).This packed-bed microreactor has been used for Knoevenagel condensation... 

Within the scope of thermoelectric nanostructures, Sima et al. [161] prepared nanorod (fibril) and microtube (tubule) arrays of PbSei. , Tej by potentiostatic electrodeposition from nitric acid solutions of Pb(N03)2, H2Se03, and Te02, using a 30 fim thick polycarbonate track-etch membrane, with pores 100-2,000 nm in diameter, as template (Cu supported). After electrodeposition the polymer membrane was dissolved in CH2CI2. Solid rods were obtained in membranes with small pores, and hollow tubes in those with large pores. The formation of microtubes rather than nanorods in the larger pores was attributed to the higher deposition current. 

Our library synthesis was carried out with a set of 27 tube-shaped solid phase synthesis support, called MicroTubes. These supports are prepared by radiation grafting of polystyrene ( — 350 pmol) onto polypropylene tubes, chemically functionalizing the polystyrene with aminomethyl groups to afford about 55 imol of amine per tube, inserting a reusable Rf ID tag into each tube, and heat-sealing the tube ends to prevent loss of the tag. The chemical conversion of all 36 aminomethyl tubes was carried out simultaneously using standard procedures with rink amide linker, each with —46 pmol of available amine per tube.1 2... 

C. Zhao, S. Shi, D. Mir, D. Hurst, R. Li, X. Y. Xiao, J. Lillig, A. W. Czamik, Polystyrene grafted fluoropolytner microtubes new supports for solid-phase organic synthesis with useful performance at high temperature. J. Comb. Chem. 1999, 1, 91-95. 

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