Diamide-diol

Synthesis of PEAs by polycondensation has usually been performed by reacting diamide-diol, diester-diamine, ester-diamine, or diamide-diester monomers with dicar-boxylic acid derivatives or diols (Figure 8.1). In addition, a,o)-amino alcohols can be also reacted with acid anhydrides or dicarboxylic acid derivatives. 

FIGURE 8.1 Diamide-diol (a, b), diester-diamine (c), ester-diamine (d), and diamide-diester (e) monomers that can be used in polycondensation reactions to get poly(ester amide)s. 

The expected fibre forming properties of poly(ester amide)s makes them suitable as bioresorbable medical sutures. Thus poly(ester amide)s based on a diamine and natural metabolites like glycolic- or lactic acid (Fig. 5.3) have been investigated. The properties of die material could be optimized by the use of water soluble diamide-diols to minimize polymer resorption time. To optimize the polymer melting temperature and in-vivo fibre strength retention succinic acid was used as die comonomer (Barrows, 1980). Alternating poly(ester... 

Pathways to segmented poly(ester-amide)s by melt polymerization of preformed diamide-diesters or diamide-diols. (b) X= OCH3, OH. 

In their studies towards new biomedical materials with fibre forming properties Barrows studied the in-vivo absorption of poly(ester amide)s (Fig. 5.3). The prineipal meehanism of in-vivo degradation appears to be hydrolysis of the ester bonds. This produees the diamide-diol monomer as a major metabolite which is non-toxic as determined by LD50 tests in rats. In separate experiments the diamide-diol monomer and the corresponding polymer showed no evidence of cytotoxicity (Barrows et al, 1986, Barrows and Horton, 1988). 

Many of the chiral molecules containing amide groups were bonded to a solid support for the preparation of CSPs [16-19]. The racemic compounds resolved on these CSPs include a-hydroxycarbonyls, /i-hydroxycarbonyls, amino acids, amino alcohols, amine, and derivatized and underivatized diols. The preliminary chiral diamide phase [(/V-foriuyl-L-valyl)aminopropyl)silica gel] has sufficient separability for racemic /Y-acylatcd a-amino acid esters but not in other types of enantiomer [16]. Most of the eluents used with these CSPs are of normal phase mode, including w-hcxanc, 2-propanol, chlorinated organic solvents, and acetonitrile. 

Benzodiazepines, profens, sulphonamidcs, P-blockers, barbiturates, hydantoins, omeprazole, mefloquine, chlorthalidone, sulphoxides, 1, r -binaphth-2,2 -diol 0.0 -bis(3,5-dimethylbenzoyl)-/V.fV -diallyl-(/ ./ )-tartaric acid diamide (Kromasil CHI-DMB) 11941... 

Compared to other anibiotics its composition is very simple — acetylene dicarbonic add diamide (8) (Suzuki and Okuma, 19S8), and it can be easily synthesised from fumaric add or from butene diol. 

Toda. F. Diol, Bisphenol, and Diamide Host Compounds. In Comprehensive Supramolecular Chemistry Atwood, J.L., Davies, J.E.D.. MacNicol, D.D., Eds. Pergamon Oxford. 1996 Vol. 6, 465-516. 

Alternating PEAs consisting of a rigid diamide-diester derived from dimethyl terephthalate and 1,4-butanediamine and flexible diol spacer building blocks of differing lengths have... 

The research team of Cramail adopted a similar strategy to prepare aliphatic diols containing monoester, diester, ester-amide, monoamide and diamide linkages from methyl 10-undecenoate derivatives [15]. Resulting diols were condensed with a methyl diester, obtained by the self-metathesis of methyl 10-undecenoate, in the presence of TBD as a transesterification catalyst. This strategy lead to various fully aliphatic polyesters and polyester-amides with Mn values of 6-19 kDa, a glass transition temperature (Tg) below room temperature (RT) and T of 22-127 °C. 

The scope of chiral recognition on these hydrogen bonding phases (mainly on diamides) has recently been shown to extend also to alcohols in the form of their carbamates, and to ketones derivatized to their oximes [12]. Furthermore, selectands which do not contain nitrogen, such as some free alcohols [10], a-hydroxy esters [11], perfluorinated acyl derivatives of sugars [13] and aromatic diols, have also been resolved on diamides. 

Selective monosubstitution in the starting dibromide by PPh2 was realized at lowtemperatures [71]. Conversion of the second bromo substituent into the phosphorus diamide and final reaction with the diol produced the hybrid ligand. In the hydroformylation of 2,5-dihydrofuran, up to 91% ee with no isomerization was achieved, which is the best value reported to date. Noteworthy, the partially hydrogenated binaphthyl unit and the phenyl substituents in the 3,3 -positions are essential for the success of the asymmetric catalysis. Related ligands with a binaphthyl backbone, with or without Me-substituents in 3,3 -positions, resulted in poor conversions and stereoselectivities. 

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