Oligo tetrahydrofurans

Koert, U. Stereoselective synthesis of oligo-tetrahydrofurans. Synthesis 1995, 115-132. 

Fleet s carbopeptoids are closely related to the oligo tetrahydrofuran amino acid sequence used in the gramicidin-like peptide developed and studied by Koert and co-workers.364 These oligo-THF peptides (Figure 52) were inserted into synthetic lipid bilayer... 

The low yields attained for the reactions shown in Scheme 3 call into doubt the usefulness of the syn-oxidative polycyclization under the published PCC-conditions for preparative purposes. However, the palette of possible oxidation reagents is by no means exhausted by PCC. Valuable ideas for a solution of the problem come from the work of Kennedy et al. with Re207 as an oxidizing agent for oxidative olefin cyclization. [6] As shown in Scheme 4 Keinan et al. [10] applied Re207 successfully in an iterative oxidative-olefin-cyclization sequence leading to oligo-tetrahydrofurans (20 -> 21 -> 22). 

A broad MWD represents a large number of macromolecules which have a wide distribution of molecular weights. The MWD of oligo-polyols is currently determined by GPC using tetrahydrofuran as solvent [21]. 

Figure 3.12 Effect of primary hydroxyl content on oligo-polyols reactivity. THF tetrahydrofuran, EO ethylene oxide...

Zimmer Comp. (Diisseldorf, Germany) and Mitsubishi Rayon Corp. (Osaka, Japan) claimed a continuous process for the production of oligo (butylene terephthalate) using catalysts based on organotitanium compounds [26]. The key point in these technologies is to produce the polycondensation at a low pressure with a view to diminishing the tetrahydrofuran content of the reaction product. 

Poly(DBF) prepared by the anionic polymerization of using 9-fluorenyllithium in tetrahydrofuran (THF) at -78 °C (M =1,070, A/ /A/n=1.38, SEC using oligo(DBF)s as the standard sample) (20 mg) and 2,4,7-ttinitrofluorenylidene-9-malononitrile (TNFMN) (1.0 mg) as an acceptor were dissolved in chloroform (1.0 mL), and the solution was cast on an indium tin oxide (ITO) glass plate and slowly dried under air to afford a thin film (thickness 5 pm). A circular Au electfode (thickness 20 nm, diameter 5 mm) was vacuum deposited onto the film to produce a sandwich-type cell for the drift mobility measurement (Fig. 27). 

This approach also enables syntheses of various multiblock copolyesters. Two strategies were elaborated. First, a polymeric cyclic initiator was prepared, for instance from oligo- or poly(ethylene glycol)s [52] or from poly(tetrahydrofuran diol)s. The subsequent REP of a lactone (see Formula 15.10, bottom) or of lactide (see Formula 15.11, top) yielded, in turn, multiblock poly(ether ester)s [53, 54]. As demonstrated in Formula 15.11, this strategy may involve spirocyclic Ge-initiators [54]. Another variant of this strategy was realized in such a way that in the first step acyclic amorphous copolymer was prepared from s-caprolactone and... 

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