Itaconic acid, reduction

Isoihamnetin la 323 Isothiazolone, microbiocidal la 45 Isothiocyanates la 75 lb 312 Isothiocyanate anions lb 307 Isotopes, detection limits la 41 Itaconic acid, reduction la 61 lodazide reaction lb 301,303... 

Isomerization has been observed with many a,j3-unsaturated carboxylic acids such as w-cinnamic 10), angelic, maleic, and itaconic acids (94). The possibility of catalyzing the interconversion of, for example, 2-ethyl-butadiene and 3-methylpenta-l,3-diene has not apparently been explored. The cobalt cyanide hydride will also catalyze the isomerization of epoxides to ketones (even terminal epoxides give ketones, not aldehydes) as well as their reduction to alcohols. Since the yield of ketone increases with pH, it was suggested that reduction involved reaction with the hydride [Co" (CN)jH] and isomerization reaction with [Co (CN)j] 103). A related reaction is the decomposition of 2-bromoethanol to acetaldehyde... 

Here, an example is given for the reduction of itaconic acid (51) with a rhodium catalyst precursor (52) and a phosphine ligand (53) (Scheme 20.18). The... 

Scheme 20.18 Reduction of the C-C double bond of itaconic acid (51) utilizing a rhodium catalyst (54) and formic acid (49) as hydrogen donor.

Mention should also be made of the DuPhos-type hybrid 10 that works well for the reductions of itaconic acids [62]. A recent addition to the general class is trichickenfootphos (11) this has been developed for the reduction of enamides, dehydroamino acids and a,/ -unsaturated nitriles [63, 64]. (Throughout this chapter, R in generic structures denotes an alkyl group unless otherwise stated.)... 

With ferrocenes, an alternative approach has been to attach the phosphorus moieties only to side chains. The WalPhos family (36) forms an eight-mem-bered chelate with the metal. Members of this family provide good selectivity and reactivity for the reductions of dehydroamino and itaconic acid derivatives as well as a,/ -unsaturated carboxylic acids [145, 156],... 

Wilkinson s (I) discovery that the soluble rhodium(I) phosphine complex, [Rh(PPh3)3Cl], was capable of homogeneous catalytic hydrogenation of olefins immediately set off efforts at modifying the system for asymmetric synthesis. This was made possible by the parallel development of synthetic methods for obtaining chiral tertiary phosphines by Horner (2) and Mislow (3,4, 5). Almost simultaneously, Knowles (6) and Horner (7) published their results on the reduction of atropic acid (6), itaconic acid (6), a-ethylstyrene (7) and a-methoxystyrene (7). Both used chiral methylphenyl-n-propyl-phosphine coordinated to rhodium(I) as the catalyst. The optical yields were modest, ranging from 3 to 15%. 

The asymmetric hydrogenation of itaconic acid (Scheme 21) and its derivatives132 has become adopted as something of a standard by which catalysts are compared. A selection of results is given in Table 2 (e.e.s only)133,76. Further applications of related reductions include the synthesis of the Renin inhibitor subunit 12 by reduction of 13 in 95% e.e.132 and the protease inhibitor 14 by reduction of 15 in this case in up to 84% e.e.134. For these processes the ligands of choice were either BINAP (in conjunction with Ru) or a derivative of BPPM (P7). 

TABLE 2. Reductions of itaconic acid with representative Rh(I) or Ru(II)/chiral diphosphine complexes (Scheme 21)... 

Hydrogenation of itaconic acid (14) with Rh(COD)Cl2 catalyst and commercially available triethylammonium formate as hydrogen source delivers (5)-(15) in good enantiomeric excess (equation 14) with hydrogen as reductant instead of ammonium formate a 94% ee is obtained. ... 

The reduction of itaconic acid derivatives was found to be selective and was used to access compounds under investigation as HIV protease inhibitors (Fig. 9) [26-28],... 

Hydrogenation of simple alkenes often serves as a test reaction to characterize the catalytic performance of new hydrogenation catalysts, and only in relatively few cases was it employed for straightforward synthetic purposes. In aqueous solutions the most widely employed substrates for catalyst characterization are unsaturated carboxylic acids (such as maleic, fumaric, crotonic, and itaconic acids), alcohols (i.e., allyl alcohol) and sodium 4-styrenesulfonate, while in two-phase hydrogenations a-alkenes (1-hexene, 1-octene), cydohexene, and styrene are the conventional targets of catalytic reduction. These reactions will not be discussed here in detail. 

In hydrogenations with H2 in D20 the product showed only CHD— stretches in the infrared. This observation excludes a fast H/D exchange on Pd, and implies a monohydridic mechanism of hydrogenation. With the same catalyst in an aqueous (D20) solution, itaconic acid is reduced under H2 to yield multiply deuterated methyl succinic acid having 1.97 deuterons at C3, 0.66 at C2 and none at Cl (Eq. 32) [83]. On the other hand, in an H20/ethyl acetate biphasic solvent mixture, the catalyst prepared in situ from [Rh(cod)Cl]2 and TPPTS catalyzed the reduction (with D2) of dimethyl itaconate with deuterium incorporation at C3 (2.06), C2 (0.78) and at Cl (0.18) [84], Similar results were obtained in toluene/methanol (1 1) with the Rh(I)-BPPM cationic catalyst [85], Again, these findings could be explained by a fast /3-elimination from the intermediate Rh(I)-alkyl. 

We proved this presumption on blends of PA6 with LDPE and HOPE and on a blend of PE with ethylene-propylene rubber (EPDM). The polyolefin components were functionalized by grafting 1 wt% of itaconic acid (lA) (51,53). Functionalization and preparation of the blends were performed in a static mixer assembled onto the Brabender plastograph (51,73). Grafting with simultaneous cross-linking of PO resulted in a sharp reduction of MFl values and r] of their melt. It can be seen in Table 18.1 that g-POs possess much higher melt viscosities than PA6. The viscosity of LDPE exceeds r] of PA6 by two decimal orders. of PA6 is twice as low as that of... 

Huang and co-workers (54) prepared copper/poly(itaconic acid-co-acrylic acid) nanocomposites via in situ chemical reduction of the Cu -polymer complex by hydrazine hydrate aqueous solution. 

The synthesis of 4-carboxy-2-piperidone entailed addition of hydrogen cyanide to dialkyl itaconate, emd reductive cycliza-tion of the resulting dialkyl cyanomethyl succinate to 4-alkoxy-carbonyl-2-piperidone followed by saponification (7). The other member of this group, 4-c u boxy-2-pyrrolldone, was obtained from its methylester which was synthesized via esterification of amino methyl succinic acid (B). The 6,6 dimethyl-4-carboxy-2-plperidone was synthesized by reductive cyclization of methyl 3-methoxy-... 

Asymmetric Hydrogenation.—The asymmetric hydrogenation of a-acylamino-acrylates and cinnamates using chiral rhodium(i) diphosphine complexes as catalysts is now established as one of the best methods for obtaining optically pure a-amino-acids (see previous reviews in this series). In the past year, some new chiral diphosphines have been added to the already considerable number of such ligands. A bis(diphenylphosphino)-derivative of pyrrolidine in conjunction with Rh can be used to hydrogenate a-acetamidocinnamates and itaconic acid with chiral inductions of 90%, whereas an Rh -diphos complex derived from natural tartaric acid effects the reduction of some a-acylaminoacrylic acids to natural (5)-a-acylamino-acids with optical yields of between 80 and 100%. ... 

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