Itaconate derivatives alkyl

Although they are often considered as poorer ligands than diphosphines, they lead also to very efficient and attractive enantioselective catalytic systems as exemplified here. As recent examples, diphosphinites 19 and 20 have been involved successfully in hydrogenation of olefins (mostly itaconate derivatives and enamides, up to > 99.9 % ee) ([84-89] and functionalized ketones (21) (up to 86 % ee) [90], hydrocyanation (19) [91], standard Pd-mediated allylic alkylation (20) [92] (up to 86% ee) [93], and Diels-Alder reaction between a,/l-enals and dienes (eq. (4) 99 % ee) [94]. 

Since the formation of Complex 11 from 10b is a second-order process and the formation of product from Complex 11 is a first-order process, their entropies of activation will be very different. A value of AS f = -121 J mol 1deg 1 has been reported for hydrogen addition to Yaska s compound, carbonylchloro bis-triphenylphosphineiridium(I) (12). As pointed out by Halpern (II), formation of the alkyl will be favored at low temperatures and it is observed to decay rapidly above -40°C. The observation and characterization of Complex 11 proved to be both fortunate and fortuitous, since we were unsuccessful in all of our attempts to form alkyls from chiraphos or DIOP, or from DiPAMP with itaconic acid derivatives. 

Finally, several examples of the enantioselective hydrogenation of unsaturated substrates without any heteroatom attached to the olefinic double bond are noteworthy. Of particular relevance to the production of pharmaceutics, agrochemicals, flavors and aroma stuffs is the formation of the chiral 2-substituted succinates based on relevant itaconic acid derivatives. Burk et al. demonstrated that a rhodium(I) catalyst derived from (5,5)-ethyl-DuPHOS is able to hydrogenate aryl- or alkyl-substituted itaconic... 

Since polymerizations of maleic acid and various alkyl esters were mentioned earlier, the derivatives of maleic add discussed below are fumaric acid and dialkylfumarates, maleonitrile and fumaronitrile, maleimide and its N-substituted derivatives, and methylene succinic acid and its anhydride (itaconic anhydride). 

Fig. 12. Damping spectra for a series of poly(di-n-alkyl itaconate)s. Methyl (A), ethyl (B), propyl (C), butyl (D), pentyl (E), and hexyl (F) derivatives. The p relaxation can only be resolved in (A), (B), and (C). ("Reproduced from J.M.G. Cowie, S.A.E. Henshall, I.J. McEwen, and J. Velickovic, Polymer, 18, 612 (1977), by permission of the publishers, Butterworth and Co. (Publishers) Ltd. ").

The sulfosuccinimdes may be of two varieties, one analogous to the previously mentioned succinic acid derivatives, where the sulfonate group is added across the double bond of maleic acid and subsequently reacted to produce the cyclic imide. The second variety requires a different synthetic approach, since the locations of their hydrophilic and hydrophobic groups are reversed from those of the succinic acid derivatives. In this case, the starting material is a 2-alkyl, alkenyl, or similar succinic anhydride, which is reacted with the appropriate sulfoalkylamine to produce the amide acid, followed by dehydration to the imide. Similar reaction schemes can be used to prepare di- and higher polyesters and amides of malonic acid, itaconic acid, and other polycarboxylic acids. 

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