Oligo synthesis

In addition, Dose and Seitz (2005) employed native chemical ligation to synthesize peptide nucleic acids (PNAs) by linking shorter segments of PNAs to make long contiguous strands, which could not be made through typical oligo synthesis procedures. 

VII. Large-scale oligo synthesis Produce sufficient oligo that meet GMP (Good Manufacture Practice) regulation... 

By the reaction of bromotoluene with ethylene under pressure, p-methylsty-rene and stilbene (45) are obtained[44,45]. A polymer 47 is obtained by the reaction of >-bromostyrene (46) with ethylene. The reaction has been applied to polymer synthesis[46]. One example is the reaction of 1,4-divinylbenzcne (48) with 9,10-dibromoanthracene to give the oligo(arylenevinylene)s 49[47]. 

The authors developed two general concepts for the synthesis of these mono-disperse, defined oligomers. The oligomers can be built up in a stepwise fashion, e.g. via addition of organomelallic species to cyclohexane-1,4-dione followed by aromatization to the oligo(arylene) (e.g. for 25). 

Table 2. Synthesis of Phthalocyanines by Conversion of Substituents at the Central Metal Giving (Oligo)Polymerization...

Phospholes can readily be prepared on a large scale and are known with a vast range of substituants [6, 16b,c]. However, the synthesis of oligo(phosphole)s analogous to (C) (Fig. 1) is a real synthetic challenge since the low aromatic character of phosphole prevents the functionalisation of the P-Ca,a carbon atoms via electrophilic substitution and inhibits their preparation using electropolymerisation. As a consequence, no poly(phosphole)s have yet been reported, although bi- and tetra-phospholes have been prepared by stepwise routes (Scheme 2). 

Based on the results of the synthesis of oligo- and poly(para-phenylene)s PPPs (see Sects. 2.1-2.3) several investigators have studied the generation of other oligo- and polyarylenes. 

Oligo- and polyarylenevinylenes are available via a variety of different, often very powerful, synthetic approaches the next section will give a brief overview of the most common strategies to generate this type of structures. In this context, emphasis will be placed on the synthesis of structurally defined and well-characterized materials. 

Type I disorders are due to mutations in genes encoding enzymes (eg, phosphomannomutase-2 [PMM-2], causing CDG la) involved in the synthesis of dolichol-P-P-oligo-saccharide... 

C. Oligo- and Poly-nucleotides.—The stepwise enzymatic synthesis of internucleotide bonds has been reviewed. A number of polynucleotides containing modified bases have been synthesised " in the past year from nucleoside triphosphates with the aid of a polymerase enzyme, and the enzymatic synthesis of oligodeoxyribonucleotides using terminal deoxynucleotidyl transferase has been studied. Primer-independent polynucleotide phosphorylase from Micrococcus luteus has been attached to cellulose after the latter has been activated with cyanogen bromide. The preparation of insolubilized enzyme has enabled large quantities of synthetic polynucleotides to be made. The soluble enzyme has been used to prepare various modified polycytidylic acids. ... 

With the exception of reaction (3), the utility of all of the above reactions for the synthesis of oligo- and polysilazanes has been examined in varying detail. In the following paragraphs, we attempt to examine the pertinent studies in each area especially as it relates to the synthesis of preceramic polymers. 

The simplicity of the ammonolysls/amlnolysis of dlhalohalosHanes, reactions (6) and (7), made them the original method of choice for the synthesis of oligo- and polysilazanes, especially because of the analogy to the hydrolytic synthesis of polysiloxanes. The ammonolysls of dihalosilanes, reaction (6), has been found to be extremely sensitive to steric factors (6). 

Catalytic dehydrocoupling, as shown in reaction (3), was pioneered by Fink (6-10) and later studied by Andrianov et al (43). Although Fink described the synthesis of the first polysilazanes, (9) reaction (23), this route to oligo- and polysilazanes remained unexplored... 

This method was first applied to the synthesis of organotin epoxy oligo-... 

A synthesis of comblike organoboron polymer/boron stabilized imidoanion hybrids was examined via reactions of poly(organoboron halides) with 1-hexylamine and oligo(ethylene oxide) monomethyl ether and subsequent neutralization with lithium hydride (scheme 8). The obtained polymers (10) were amorphous soft solids soluble in common organic solvents such as methanol, THF, and chloroform. In the nB-NMR spectra (Fig. 11), neutralization of the iminoborane unit with lithium hydride... 

Inoue and Orgel (1981) found that the oligomerisation of guanosine-5 -phosphoimidazolide on a poly(C) matrix can take place in the absence of Pb2+ or Zn2+, if guanosine-5 -phospho-2-methylimidazolide is used for the oligo-G synthesis. 

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