Amino olefin complexes

Djordjevic et al.464 have described the synthesis and characterization of amino acid complexes MoO(02)2Leq(OH2) (192) and the X-ray structures of the Gly, Ala, and Pro derivatives. Chiral ligands such as (R)/(S)-(194), (R)/(S)-(195), and (RR,S)/(R,SR)-(196) form Mimoun complexes, MoO(02)2L and MoO(02)2L(OH2). IR and 31P NMR data, as well as the X-ray structure of pentagonal bipyramidal MoO(02)2(R,R,.S -196)(OH2), indicate the presence of equatorial phos-phoryl donors.465,466 Enantioselectivity in the stoichiometric epoxidation of pro-chiral olefins was marginal (<10%) except in the case of the binaphthyl derivatives (L - 195) where e.e. s of up to 39% were recorded.4 Related structures are observed for phosphine oxide458,467 and chelate complexes such as MoO(02)2 OE(iPr)2CH2CH2OMe (197, E = P, As) 458 468 An efficient bipha-sic catalytic epoxidation system based on MoO(02)2(OPR3) (R = -dodecyl) has been developed and the activity of related complexes assessed.460 Earlier attempts to produce aqueous oxidants included the synthesis of water-soluble bpy derivatives.469,470... 

V. B. Valodkar, G. L. Tembe, R. N. Ram, H. S. Rama, Catalytic asymmetric epoxidation of unfunctionalized olefins by supported Cu(II)-amino acid complexes, Catal. Lett. 90 (2003) 91. 

Carbonylation of cyclic amines, hydroformylation (CO-H2) of amino olefins catalyzed by metal (Pd, Ru, Rh) complexes (see 1st edition). 

Complexes with this formulation satisfy the generally accepted criteria for structural features required in an antitumor-active platinum complex, but are expected to possess kinetic advantages when compared to the prototype antitumor platinum complex, cis-dichloro-diamineplatinum (II). Complexes have been prepared where L is a monoprotonated diamine and also where L is a protonated amino-olefin. All complexes have been examined for cytotoxicity against L1210 leukemia in cell culture, and selected compounds have been tested for antitumor activity vivo (LI210 leukemia in BDF mice). One compound, where L is protonated 3-amino-quinuclidine, has significant vivo activity, with T/C approaching 150%. 

Such complexes can in fact, as well as in principle, exhibit significant antitumor activity. We report here the synthesis, characterization, and antitumor activity of two broad classes of complex having structure II, those where the positively charged ligand is a monoprotonated (or monoalkylated) diamine and those where it is a monoprotonated amino-olefin. 

In the absence of protonation, the neutral amino-olefin is, in principle, capable of coordination as a chelate ligand, utilz-ing both the olefin ir-system and the nitrogen lone pair. This would produce a neutral complex of type V, which should also be activated toward the substitution reaction of equation (1), and. 

The insertions of enamides into rhodium hydrides have also been studied in detail (Equation 9.46). " In this case, oxidative addition of dihydrogen occurs to the olefin complex to generate the intermediate containing ds olefin and hydride ligands. This reaction controls the stereochemical outcome of enantioselective hydrogenations of enamides to form a-amino acids presented in Chapter 15. As noted in this chapter, the oxidative addition forms two diastereomeric complexes, and the less abundant diastereomer reacts much faster and forms the more abimdant enantiomeric amino acid produd. 

Prochiral olefins such as the (Z)-a-acetamidocinnamic acid derivatives, MAC and EAC, bind to the rhodium-DIPAMP catalyst to form the diastereomeric olefin complexes A and A shown in Scheme 15.18. Oxidative addition of dihydrogen to each of the diastereom-ers forms diastereomeric hydride complexes B and B, each of which imdergoes migratory insertion to form alkyl hydride complexes C and C. These complexes then undergo reductive elimination to form the amino acid ester products. The stereochemistry of the organic products can be predicted for the two parallel paths, assuming that the addition of occms to the face of the olefin coordinated to Rh. The N-acetyl-(R)-phenylalanine ester would be produced from the olefin adduct A and the (S)-product from A. ... 

In the case of the olefin (481), the n.m.r. spectrum of the mercurial shows it to be exclusively one of the two possible astereoisomers (482). Although a complexing of mercury by nitrogen could be envisaged, leading to cis addition, in fact the reaction proceeds by a formal trans addition of mercury and nitrogen across the double bond, as is shown by detailed examination of the n.m.r. spectra of products from and /roftJ-substituted amino-olefins. Reduction of (482) with sodium borohydride yielded a mixture of (483) and (484), for which an intermediate aziridinium ion is responsible. 

Diastereoselective preparation of a-alkyl-a-amino acids is also possible using chiral Schiff base nickel(II) complexes of a-amino acids as Michael donors. The synthetic route to glutamic acid derivatives consists of the addition of the nickel(II) complex of the imine derived from (.S )-,V-[2-(phenylcarbonyl)phenyl]-l-benzyl-2-pyrrolidinecarboxamide and glycine to various activated olefins, i.e., 2-propenal, 3-phenyl-2-propenal and a,(f-unsaturated esters93- A... 

In contrast to alkoxycarbene complexes, most aminocarbene complexes appear too electron-rich to undergo photodriven reaction with olefins. By replacing aliphatic amino groups with the substantially less basic aryl amino groups, modest yields of cyclobutanones were achieved (Table 10) [63], (Table 11) [64]. Both reacted with dihydropyran to give modest yields of cyclobutanone. Thio-carbene complexes appeared to enjoy reactivity similar to that of alkoxycar-benes (Eq. 15) [59]. 

The mild reaction conditions and the obviously high potential driving force of the ketene Claisen rearrangement recommended the use of the process for more complex systems. The first series of this type of reaction suffered from severe limitations. On the one hand, only electron-deficient ketenes added to the allylamines, and useful yields of the lactams had exclusively been achieved by employing dichloroketene [57, 58 a]. On the other hand, the rearrangement was restricted to either monosubstituted olefins in the amino fragment or the... 

A similar, although less marked difference characterizes the cyclopropanation of olefins 41 and 42. In the presence of either copper or copper complexes whose chelating ligands contain an azomethine moiety derived from an a-amino acid, no stereoselectivity was observed with diene 41, whereas the cyclopropanes derived from 42 occur with cisjtrans ratios of 57 43 to 69 31, depending on the catalyst93). 

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