Intermolecular transformations

Each volume will be thematic, dealing with a specific and related subject that will cover fundamental, basic aspects including synthesis, isolation, purification, physical and chemical properties, stability and reactivity, reactions involving mechanisms, intra- and intermolecular transformations, intra- and intermolecular rearrangements, applications as medicinal agents, biological and biomedical studies, pharmacological aspects, applications in material science, and industrial and structural applications. 

Intramolecular [3+2]-Cycloaddition ofNitronates These reactions are more efficient than analogous intermolecular transformations of nitronates as [1,3]-dipoles, and, consequently, activation of the dipolarophilic fragment is not required. However, another problem arises, that is, the construction of the starting substrate combining the nitronate fragment and the C,C double bond in the required positions. 

Two remarkable and unique properties of molecular encapsulation are protection against atmospheric oxidation and disproportionations between components of flavors. In addition,intermolecular transformations are almost entirely eliminated due to the surrounding cyclodextrin ring. 

Interesting intra- and intermolecular transformations involving oxonium ions formed by protonation of furan rings were shown to lead to elaborated ring systems. As shown in Scheme 1, interception of a transient cation by the pendant hydroxyl group led to the ketone intermediate 1, which further cyclized to provide the tetracyclic isochro-mene product <2005TL8439>. 

An intramolecular variation of the ene/enone photocycloaddition is described by J. D. Winkler. As already described for the intermolecular transformation (see Demuth s enone cycloaddition reaction), a dioxenone is formed via cyclization of a 3-ketoester and subsequently irradiated. Intramolecular cycloaddition then leads to a strained tetracyclic photoproduct which can be ring-opened and decarboxylated to give the trans-fused bicyclo[5.3.1 ]undecan-11 -one. 

Intramolecularization is used to describe the process of making an intermolecular transformation intramolecular, hence the verb intramolecularize for a previous use see, for example, T.-L. Ho in Tactics of Organic Synthesis, Wiley, New York, 1994, Chapter 6. 

Figure 9.7 shows molecular ligogenicities ( , values) and process ligogenicities (L r values) for various intramolecular and intermolecular transformations. The forward direction of the first intramolecular case, 123- 124, is described as the L , value of 123 is 4, and Lfor = Lm/2=... 

Figure 9.7. Molecular Ligogenicity (L value) and Process Ligogenicity (L, L , ) for Various Intramolecular and Intermolecular Transformations...

Scheme 3.7 Intermolecular transformations of aryl- and alkenylpalladium intermediates 2...

Abstract The present work describes a comprehensive review of the functionalization of cyclopropyl C-H bonds via transition-metal catalysis. Compared to the enormous number of publications related to direct sp and sp bond transformations in the last two decades, the first full account of direct cyclopropyl C(sp )-H bond functionalization was only disclosed in 2011. Both intra- and intermolecular transformations are detailed in the review, including asymmetric reactions. In addition, mechanistic aspects of various Pd-catalyzed cyclopropane functionalizations are discussed. 

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 Ma group has reported some very elegant multibond forming processes to synthesize dendralenes, including both palladium(II)- and rhodium(I)-catalyzed cycloisomerizations of di-allenes 106 to form cyclic dendralenes 107 (Scheme 1.15) [68, 69, 71], and also the remarkable palladium(0)-catalyzed three-component reaction of di-allenes 108, propargylic carbonates 109, and boronic acids 110 to form bicyclic [3]dendralenes 111 (Scheme 1.15) [70]. Similar, intermolecular transformations to those used to form dendralenes 107 had been reported earlier by Alcaide, to synthesize dihydrofuran-containing dendralenes [72, 73]. 

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