Synthesis reagents, solid supported

I 2 Supported Reagents and Scavengers in Multi-step Organic Synthesis Automated library synthesis using solid-supported reagents... 

An important difference between combinatorial or parallel DOS and, for example, total synthesis is the high number of synthesized compounds, which renders conventional purification procedures such as flash chromatography impractical, at least if they have to be performed after every step. Synthesis on solid support avoids these problems to some extent if high conversions can be achieved with excess reagent or selective release strategies (see above). To do solution phase DOS, selective, high yield reactions or selective purification processes are required. 

Integrating microwave-assisted synthesis and solid-supported reagents... 

MICROWAVE-ASSISTED SYNTHESIS AND SOLID-SUPPORTED REAGENTS... 

Ley, S.V., Baxendale, I.R., Bream, R.N., Jackson, P.S., Leach, A.G. etal, Multi-step organic synthesis using solid-supported reagents and scavengers a new paradigm in chemical library generation, J. Chem. Soc, Perkin Trans. 1, 2000, 3815. 

Petricci, E., Botta, M., Corelli, F. and Mugnaini, C., An improved synthesis of solid-supported reagents (SSRs) for selective acylation of amines by microwave irradiation, Tetrahedron Lett., 2002, 43,6507. 

It should be highlighted that in some cases the distinction between a traditional solid-phase synthesis and a process involving solid-supported reagents is often difficult. The reader is advised to refer also to the chapter on the integration of microwave-assisted synthesis with solid supported reagents and scavengers (Chapter 6). 

Although nucleophilic selenium species have already demonstrated their potential as versatile reagents in organic synthesis, their scope as useful reagents is still expanding as shown in applications towards stereoselective synthesis and synthesis on solid supports. 

This reagent, benzotriazol-l-yl-oxytripyrrolidinophosphonium hexafluorophosphate (14, PyBOP)P l (Scheme 4), was designed in order to avoid the formation of toxic HMPA during acylation. As with BOP, it is assumed that the first step is the carboxylic acid activation which involves formation of an acyloxyphosphonium salt.P This initial salt is then attacked by the benzotriazolyloxy anion to form the benzotriazolyl active ester which then reacts with the amino component. PyBOP can easily replace the BOP reagent and is especially suitable for solid-phase peptide synthesis. It is soluble in a wide range of solvents such as DMF, di-chloromethane, THF, and NMP. PyBOP is more useful in peptide synthesis on solid support than in solution. The byproduct, tris(pyrrolidino)phosphine oxide is partially water-soluble and is easily removed by washing. PyBOP is used under the same experimental conditions as BOP. Note that PyBOP is a white, crystalline and non-hygroscopic solid. It can be kept as a solid, but solutions of PyBOP cannot be stored for more than 24 hours. 

New Trends in the Synthesis of Solid-Supported Organotin Reagents 607... 

New Trends in the Synthesis of Solid-Supported Organotin Reagents and Interest of their Use in Organic Synthesis in a Concept of Green Chemistry... 

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