1,5-Diol diesters

The 1,5-diol diester 116 and the 1,3-diol diester 117 had been derived from natural p-Upomycin without the stereodescriptors of Scheme 21 already attached to them. The 3D structures of both compounds were determined by GLC comparisons (Section 8.6) with full sets of the cmiceivable stereoisomers. The syntheses of the latter were realized as described in Scheme 22 (1,5-diol diesters 116) and Scheme 23 (1,3-diol diesters 117). 

A -methyl bis(trifluoroacetamide). The resulting 1,5-diol diesters 116 were applied crude to the GLC colunui (Section 8.6, Fig. 15). 

The syntheses of all four stereoisomers of the 1,3-diol diesters 117 comprised a total of 4 X 2 steps (Scheme 23). Moreover, the four initial reactions were described in the literature. These parameters were so reassuring that MLH did not ponder the alternative of another killing-two-birds-with-one-stone approach, akin to the one that had furnished the 1,5-diol diesters 116 (Scheme 22). The first transformation of the syntheses of Scheme 23 was the NaBHt reduction of the aldols 36a anti) and 36a (ent,anti) by an in-house procedure " and the LiBli reduction of the aldols 36b ent,syn) and 36b (syn) following another literamre protocol. The second transformation was the respective bis(trifluoroacetate) formation. It was realized by treatment with an excess of Af-methyl bis(trifluoroacetamide). The resulting 1,3-diol diesters 117 were applied cmde to the GLC column (Section 8.6, Fig. 16). 

Having accomplished the very last reactions of our project (Section 8.5), the remainder seemed a piece of cake. This was all the more true since our institute hosts an analytical laboratory. They offer the convenience of effecting GLC or HPLC separations, as the case may be, of mixtures, which the researchers bring. With regard to our request they did not take long to separate all four 1,5-diol diesters 116 from one another (Fig. 15, traces 1-4) and to separate all four 1,3-diol diesters 117 from raie another, too (Fig. 16, traces 1-4). 

Under the identical conditions, a mixture of the four stereoisomeric 1,5-diol diesters 116 was resolved in four peaks (Fig. 15, trace 6) and a mixmre of the four stereoisomeric 1,3-diol diesters 117, too (Fig. 16, trace 6). When the analytical service injected the mixture of the diesters 116 and 117, which we had prepared from natural P-lipomycin as documented in Scheme 15, we held our breath, figuratively speaking. Would our sample make it onto the col-unm all right Or would a hitherto unheard of variant of Murphy s Law interfere Like having the analysis person faint after picking up our flask, dropping it, having it fall, break, and thus spill the world s supply of p-Upomycin-based diesters 116 and 117 three floors upstairs from our lab. Luckily, the GLC analysis of this ester mixture proceeded 100% routinely. ElutiOTi time comparisons revealed that the p-lipomycin-based diester 116 (Fig. 15, trace 5) was (4/ ,5S)-116 and that the p-lipomycin-based diester 117 was (4/ ,55)-117 (Fig. 16, trace 5). 

In a model study aimed at elucidating the behavior of the polymers, Watanabe found that the dimer polymethylene diol diesters of type 7 (Figure 8.18) formed smectic phases.38 When the spacer between the two mesogenic units in the dimer had an odd number of methylene groups (diester 7 has nine methylenes in the spacer), then an intercalated tilted smectic structure with all anticlinic layer interfaces was formed. This structure is often termed SmC2 in the literature. As for the B6 phase, all of the layer interfaces in this structure are equivalent, and the X-ray layer spacing is less than half the fully... 

Yang, L. and Klang, J., Polyetherester resins from diol diesters, US Patent 5 677 396, 1997. 

Kolbe oxidation of carboxylate ions to radicals with loss of carbon dioxide (p. 312). The latter process gives highest yields of dimeric product at a platinum anode and only monomeric products from oxidation of the radical centre at a carbon anode. Oxidation of butadiene in methanol containing benzoic acid, at a smooth platinum anode, gives 45 % of the but-3-ene-l,4-diol diester [45]. 

Diol lipids have been reported only recently when techniques for their stmcture elucidation were developed. Small quantities of diol lipids, such as diacylpropane-l,3-diol, diesters of butane-1,3-diol, and butane-1,4-diol are found in mammalian and fish liver, mammalian adipose tissues, egg yolk, com seed, and yeast (20). From Actynomyces olivaceus, mixed acyl- and alk-l-enyl derivatives of simple diols have been isolated (21). An acylated diol phospholipid has been produced by the yeast Lypomyces starkeyi when grown on propane-1,2-diol (22). 

The kinetics of formation of the propane-1,2-diol diester at 25 °C have been studied over the range pH 1-13 by the stopped-flow technique (Buist and Bun-ton ). The reaction is general base catalysed and shows many of the features found in the kinetics of the oxidation of pinacol (next section). 

The synthesis of 1,3-diol diesters through a coupling reaction with aldehydes and oxime esters catalyzed by bis(pentamethylcyclopentadienyl)samarium has been reported (Scheme 311).1101... 

On the other hand, nickel complexes give acyloins or en-diol diesters. 

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. 

DL-1,2 3,4-Diepoxybutane ( )-1,2 3,4-Diepoxybutane. See DL-Diepoxybutane Diester/ether diol of tetrabromophthalic anhydride. See Tetrabromophthalic anhydride, diester/ether diol Diester oils... 

Motivated by the desirable lubricant-related properties obtained for diol diesters of pHAs discussed above and the desirable properties (low pour point and high VI) and biodegradability of polyol-fatty acid ester lubricants (26,44-46), star polymers consisting of a polyol core [e.g., pentaerythritol (PE), trimethylolpropane (TMP), or dimer diol (DD)] and pRA arms (Figure 1) were synthesized in bulk at 70°C using CAL as biocatalyst in our laboratory within a 1-week period. DD is a biolubricant material derived chemically from unsaturated fatty acids. 

Diester/Ether Diol of Tetrabromophthalic Anhydride. This material [77098-07-8] is prepared from TBPA in a two-step reaction. First TBPA reacts with diethylene glycol to produce an acid ester. The acid ester and propylene oxide then react to give a diester. The final product, a triol having two primary and one secondary hydroxyl group, is used exclusively as a flame retardant for rigid polyurethane foam (53,54). 

Diesters. Diesters prepared from the diol and monocarboxyhc acids are useful as antioxidants (qv) for polypropylene (98), and as plasticizers... 

A smaller but rapidly growing area is the use of PTMEG ia thermoplastic polyester elastomers. Formation of such polyesters iavolves the reaction of PTMEG with diacids or diesters. The diols become soft segments ia the resulting elastomeric materials. Examples of elastomeric PTMEG polyesters iaclude Hytrel (Du Pont) and Ecdel (Eastman Chemicals). 

Titanium-cataly2ed ester interchange can be used to prepare polyesters from diester and diols as well as from diacids and diols at considerably higher temperatures. Polymer chains bearing pendant ester and hydroxy functions can be cross-linked with titanates. 

A number of examples of monoacylated diols produced by enzymatic hydrolysis of prochiral carboxylates are presented in Table 3. PLE-catalyzed conversions of acycHc diesters strongly depend on the stmcture of the substituent and are usually poor for alkyl derivatives. Lipases are much less sensitive to the stmcture of the side chain the yields and selectivity of the hydrolysis of both alkyl (26) and aryl (24) derivatives are similar. The enzyme selectivity depends not only on the stmcture of the alcohol, but also on the nature of the acyl moiety (48). 

These xylylene groups are typically available commercially , by halogenation of xylenes ", by halomethylation of an aromatic" or by conversion of a diester into its corresponding diol followed by halogen-hydroxyl interconversion . 

Epoxides are easily attacked by trifluoroacetic anhydride. The reactions lead to diesters of vicinal diols and monoesters of unsaturated allylic alcohols in ratios depending on the reaction conditions [24] (equation 13). 

The general procedures for the preparations of half-esters of diols are not usually very efficient in that both unreacted diol and diester are present along with the desired half-ester. Unfortunately, the present example is no exception but is included as an illustration of the type of results that can be expected under these circumstances. The diol employed for this reaction is prepared in Chapter 5, Section II. 

Chifdl rraildple-coupLing reageats have beea prepared in enandomerically pure form by enando-selecdve saporuficadon of diesters of meso-2-nitrQcyclohexane-1,3-diols fEq. 3.44 widi pig liver esterase fPLEi. ... 

Step-growth polymers, the second major class of polymers, are prepared by reactions between difunctional molecules, with the individual bonds in the polymer formed independently of one another. Polycarbonates are formed from a diester and a diol, and polyurethanes are formed from a diisocyanate and a diol. 

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