Intramolecular organic transformation

Generally, hydrocarbons tethered with sulfamate esters or carbamates are suitable substrates and afford five- or six-membered ring products through intramolecular C-H amidation. For reasons not yet understood, carbamates and sulfamate esters prefer to form five- and six-membered rings, respectively. In general, this important and useful selectivity can avoid formation of product mixtures, a major drawback for similar organic transformations. 

With regards to oxidative reactivity, it seems that dicopper(II) end-on peroxo complexes are basic, or nucleophilic, in nature, without oxidizing substrates such as PPha or 2,4-di-tert-butylphenol. Instead, O2 is released and PPhs binds, or deprotonation of the phenol occurs leading to a Cu -hydroperoxide. By contrast, the side-on bound dicopper(II) peroxide and its isoelectronic isomer, the dicopper(III) bis(p-oxo) species, both are electrophilic and have been shown to react with a wide array of substrates, in intramolecular (ligand) oxidations, and intermolecular organic transformations. Our group has extended the oxidative capability of CU2O2 complexes to novel (for copper chemistry) substrates such as tetrahydrofuran and dimethylaniline, which are oxidized to 2-hydroxy-tetrahydrofuran, and methylaniline plus formaldehyde, respectively. 

This area of research most probably began when Semmelhack and co-workers reported both inter- and intramolecular versions of Ni-catalyzed arylation of lithium enolates derived from ketones shown in Scheme 7,[i5],[i6] jjjjg vork, however, was not developed further perhaps due, at least in part, to the fact that the same organic transformation was achieved much more satisfactorily by resorting to the SrnI reaction. ... 

Cascade intermolecular carbopalladations of alkynes followed by intramolecular trapping with electrophiles represent not only a novel type of organic transformation involving vinylpalladium intermediates, but also provide synthetically useful routes toward differently substituted indenols, indanones, indenones, and naphthy-lamines." Although these protocols are restricted to the intramolecular trapping with electrophiles, a wide application of this methodology toward the synthesis of various types of complex carbocychc compounds may be anticipated in the near future. 

Organolanthanide complexes are known to be highly active catalysts for a variety of organic transformations, which can be either intramolecular or intermolecular in character. Successful intramolecular transformations include hydroelementation processes, which is the addition of a H-E (E = N, O, P, Si, S, H) bond across unsaturated C-C bonds, such as hydroamination, hydroalkoxylation, and hydrophosphination. Intermolecular transformations include a series of asymmetric syntheses, the amidation of aldehydes with amines, Tishchenko reaction, addition of amines to nitriles, aUcyne dimerization, and guanylation of terminal aUcynes, amines, and phosphines with carbodiimides. 

The catalytic activity of 4 in intermolecular hydroamination of alkynes by anilines as well as in the intramolecular alkene and alkyne hydroamination has been reported [40]. The results show that in the presence of ]PhNMe2H+][B(CgF5) ], 4 could catalyze these reactions very efficiently (2.5 mol% catalyst, 20 - 80 °C). It was su ested that the Cp moiety was protonolyzed to give Cp H, which was identified by NMR. In most cases, excellent yields were achieved, indicating a possible high potential of Zn-Zn-bonded complexes for catalytic organic transformations. As the presumed mechanism is not discussed further, it is hitherto unclear whether a Zn species is prevalent in the catalytic cycle. 

Among the variety of organic transformations that are amenable to organocatalysis, the ring-forming reactions occupy a predominant position for efficient constructions of chiral carbo- and heterocycles [4]. In fact, the L-prolineintramolecular asymmetric aldol reaction of a triketone compound was reported by two industrial research groups as early as 1971 [5],... 

Due to its marked atom economy, the intramolecular hydroamination of alkenes represents an attractive process for the catalytic synthesis of nitrogen-containing organic compounds. Moreover, the nitrogen heterocycles obtained by hydroamination/cyclisation processes are frequently found in numerous pharmacologically active products. The pioneering work in this area was reported by Marks et al. who have used lanthanocenes to perform hydroamination/cyclisation reactions in 1992. These reactions can be performed in an intermolecular fashion and transition metals are by far the more efficient catalysts for promotion of these transformations via activation of the... 

This chapter deals with [2 + 2]cycloadditions of various chromophors to an olefinic double bond with formation of a four-membered ring, with reactions proceeding as well in an intermolecular as in an intramolecular pattern. Due to the variety of the starting materials available (ketones, enones, olefins, imines, thioketones, etc.. . .), due to the diversity of products obtained, and last but not least, due to the fact that cyclobutanes and oxetanes are not accessible by such a simple one-step transformation in a non-photo-chemical reaction, the [2+2]photocycloaddition has become equivalent to the (thermal) Diels-Alder reaction in importance as for ring construction in organic synthesis. 

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