Coupling with solid-phase

Hawthorne SB, Grabanski CB, Hageman KJ, Miller DJ. Simple method for estimating polychlorinated biphenyl concentrations on soils and sediments using subcriti-cal water extraction coupled with solid-phase microextraction. J. Chromatogr. A 1998 814 151-160. 

Methylimidazole was arylated only once with solid phase bound (chloromethyl polystyrene as solid phase precursor) aryl iodide 409. Depending on the choice of catalyst, 1-methylimidazole coupled with solid phase bound aryl iodide in 67% yield at the 5-position when Pd(OAc)2 and PPh3 were used as the catalyst system. However, when Cul was added to the above catalyst system, the only product isolated was the 2-arylated imidazole 411 in 49% yield. No diarylation product was found using either reaction system (Scheme 99) <20000L3111>. 

Fig. 1 Chromatogram of PAHs, herbicides, and phenols obtained by supercritical carbon dioxide modified with methanol. [Reprinted from L. Toribio, M. J. del Nozal, J. L. Bernal, J. J. Jimenez, and M. L. Serna, Packed-column supercritical fluid chromatography coupled with solid-phase extraction for the determination of organic microcontaminants in water,...

Palmira Arenaz-Laborda, M., Extraction of polycyclic aromatic hydrocarbons from soil using hot water extraction coupled with solid phase microextraction , MSc Dissertation, Northumbria University, Newcastle, UK, 1998. 

Ultrasonic LSE is most applicable to the isolation of semivolatile and nonvolatile organic compounds from solid matrices such as soil, sediment, clays, sand, coal tar, and other related solid wastes. U-LSE is also very useful for the disruption of biological material such as serum or tissue. U-LSE can be coupled with solid-phase extraction (SPE) to give a very robust sample preparation method at relatively low cost in comparison to MAE and ASE approaches. The author has utilized U-LSE/SPE to isolate and recover 9,10-dimethyl-l,2-benzanthracene from animal bedding. A 89% recovery was obtained for bedding that was spiked with this polycyclic aromatic hydrocarbon (PAH) of interest to toxicologists (20). An ultrasonic horn and tip are immersed into a mixture of liquid extractant and solid sample and sonicated at some percent of full power for a finite length of time, either continuously or pulsed. 

Inoue, K. Okada, R Ito, R. Kawaguchi, M. Okanouchi, N. Nakazawa, H. Determination of perfluorooctane sulfonate, perfluorooctanoate and perfluorooctane sutfonylamide in human plasma by column-switching liquid chromatogra-phy-electrospray mass spectrometry coupled with solid-phase extraction. J. Chromatogr. B, 2004, 810,49. 

Xu, N., Vandergrift, S., Sewell, G.W. (1996) Determination of chioroethenes in environmental biological samples using gas chromatography coupled with solid phase micro extraction. Chromatographia, 42, 5. 

Toribio, L. et al.. Packed-column supercritical fluid chromatography coupled with solid-phase extraction for the determination of organic microcontaminants in water, /. Chromatogr. A, 823, 163,1998. 

Then N-Boc-O-benzylserine is coupled to the free amino group with DCC. This concludes one cycle (N° -deprotection, neutralization, coupling) in solid-phase synthesis. All three steps can be driven to very high total yields (< 99.5%) since excesses of Boc-amino acids and DCC (about fourfold) in CHjClj can be used and since side-reactions which lead to soluble products do not lower the yield of condensation product. One side-reaction in DCC-promoted condensations leads to N-acylated ureas. These products will remain in solution and not reaa with the polymer-bound amine. At the end of the reaction time, the polymer is filtered off and washed. The times consumed for 99% completion of condensation vary from 5 min for small amino acids to several hours for a bulky amino acid, e.g. Boc-Ile, with other bulky amino acids on a resin. A new cycle can begin without any workup problems (R.B. Merrifield, 1969 B.W. Erickson, 1976 M. Bodanszky, 1976). 

H. M. M. Arafa, E. M. A. Hamada, M. M. A. Elzamai and H. Nau, Eully automated detemination of selective retinoic acid receptor ligands in mouse plasma and tissue by reversed-phase liquid chi omatography coupled on-line with solid-phase extraction , 7. Chromatogr. A 729 125-136 (1996). 

Figure 13.19 Chromatograms obtained by on-line SPE-GC-MS(SIM) of (a) 10 ml of tap water spiked with pesticides at levels of 0.1 ng 1 (b) 10 ml of a sample of unspiked tap water. Peak identification foi (a) is as follows 1, molinate 2, a-HCH 3, dimethoate 4, simazine 5, ati azine 6, y-HCH 7, S-HCH 8, heptachloi 9, ametiyn 10, prometiyn 11, fen-itrothion 12, aldrin 13, malatliion 14, endo-heptachlor 15, a-endosulfan 16, teti achlor-vinphos 17, dieldrin. Reprinted from Journal of Chromatography, A 818, E. Pocumll et al., On-line coupling of solid-phase exti action to gas cliromatography with mass specti ometiic detection to determine pesticides in water , pp. 85-93, copyright 1998, with permission from Elsevier Science.

E. Pocurull, C. Aguilar, E. Borrull and R. M. Marce, On-line coupling of solid-phase extraction to gas cliromatography with mass spectrometric detection to determine pesticides in water , 7. Chromatogr. 818 85-93 (1998). 

Niederlander H.A.G. et al., 2006. High throughtput therapeutic drug monitoring of clozapine and metabolites in serum by online coupling of solid phase extraction with liquid chromatography-mass spectrometry. J Chromatogr B 834 98. 

Due to the vast numbers and rapidity of novel developments in solid-phase synthesis over the past ten years, a number of reports currently found in the literature deal with solid-phase syntheses of lanthionine peptides. There are at least two different approaches to synthesize lanthionine peptides in which the sulfide bond links amino acid halves that are not direct neighbors within the peptide chain (Scheme 10). One obvious approach, method A, is based on the coupling of a preformed, orthogonally protected lanthionine monomer to the N-terminus of a peptide oxime resin. 48 This is then followed by acid-catalyzed cyclization and simultaneous release from the resin during amide bond formation with the C-terminal carboxy group via the peptide cyclization method on oxime resin (see Section 6.73.2.2). The alternative approach is lanthionine formation after peptide synthesis from amino acid derivatives, such as serine and cysteine (method B). 

Hankemeier TH, Louter AJH, Rinkema FD, et al. 1995. On-line coupling of solid-phase extraction and gas chromatography with atomic emission detection for analysis of trace pollutants in aqueous samples. Chromatographia 40(3-4) 119-124. 

The development of chiral peptide-based metal catalysts has also been studied. The group of Gilbertson has synthesized several phosphine-modified amino adds and incorporated two of them into short peptide sequences.[45J,71 They demonstrated the formation of several metal complexes, in particular Rh complexes, and reported their structure as well as their ability to catalyze enantioselectively certain hydrogenation reactions.[481 While the enantioselectivities observed are modest so far, optimization through combinatorial synthesis will probably lead to useful catalysts. The synthesis of the sulfide protected form of both Fmoc- and Boc-dicyclohexylphosphinoserine 49 and -diphenylphosphinoserine 50 has been reported, in addition to diphenylphosphino-L-proline 51 (Scheme 14).[49 To show their compatibility with solid-phase peptide synthesis, they were incorporated into hydrophobic peptides, such as dodecapeptide 53, using the standard Fmoc protocol (Scheme 15).[451 For better results, the phosphine-modified amino acid 50 was coupled as a Fmoc-protected dipeptide 56, rather than the usual Fmoc derivative 52.[471 As an illustrative example, the synthesis of diphe-nylphosphinoserine 52 is depicted in Scheme 16J45 ... 

---