Hydrofunctionalization

Table of Contents

1. Frontmatter

2. Alkyne and Alkene Insertion into Metal–Heteroatom and Metal–Hydrogen Bonds: The Key Stages of Hydrofunctionalization Process

   Valentine P. Ananikov, Irina P. Beletskaya

   Abstract

   In this chapter we review mechanistic concepts of carbon–heteroatom bond formation involving hydrofunctionalization of double and triple carbon–carbon bonds via migratory insertion pathway. A variety of useful synthetic procedures were developed within the scope of hydrofunctionalization reaction involving transition metal catalysts to change the direction of the addition reaction and to improve the selectivity of the process. Outstanding potential of multiple bonds activation and insertion in the metal complexes is far from being fully explored. The key factors determining insertion pathways into metal–heteroatom vs. metal–hydrogen bonds and the influence on regioselectivity of the insertion remain to be revealed in nearest future.

3. The Mechanism for Transition-Metal-Catalyzed Hydrochalcogenation of Unsaturated Organic Molecules

   Akihiko Ishii, Norio Nakata

   Abstract

   In this chapter, discussions are focused on two types of mechanisms of transition-metal-catalyzed hydrochalcogenation, Type I and Type II, which are classified by the initial behavior of precatalysts. In Type I mechanism, precatalyst M–X (M = Pd, Ni, Zr, Ln, and An) first undergoes protonolysis with REH (E = O, S, and Se) to generate active catalyst M–ER, which then undergoes insertion of alkyne into the M–ER bond (chalcogenometalation) to give 2-chalcogenovinyl complex, followed by protonolysis of M–C_vinyl with REH to produce the product and to regenerate active catalyst M–ER. Type II mechanism starts from oxidative addition of REH (E = S and Se) to complex [M] (M = Pd, Pt, Rh, and Ir) to give chalcogenolato–hydrido complex, [M]H(ER). In the next alkyne insertion, [M]–H insertion (hydrometalation) to give [M](ER)(vinyl) or [M]–E insertion (chalcogenometalation) to give [M]H(2-RE-vinyl) occurs and then reductive elimination of the resulting vinyl [M] complexes yields the product and [M]. Reactions where transition metal catalysts exert as Lewis acid to activate unsaturated bonds and those proceeding through vinylidene intermediates are mentioned only shortly.

4. Early Transition Metal (Group 3–5, Lanthanides and Actinides) and Main Group Metal (Group 1, 2, and 13) Catalyzed Hydroamination

   Alexander L. Reznichenko, Kai C. Hultzsch

   Abstract

   The hydroamination of alkenes, dienes, allenes, and alkynes by early transition metal catalysts has seen significant progress over the last decade, especially with respect to control of regio- and stereoselectivity and the synthesis of more complex nitrogen-containing skeletons. This article provides an overview over the application of catalyst systems based on the 17 rare earth elements, as well as group 4 and group 5 metals. These electropositive metal catalysts operate via activation of the amine to form catalytic active metal-amido or metal-imido species, although the true nature of this species is not known with certainty for all systems and may vary for different substrate classes. This mode of activation differentiates early transition metal catalysts from many late transition metal catalysts that operate via activation of the unsaturated C–C linkage (alkene, 1,3-diene, allene, or alkyne). Alkali metals, alkaline earth metals and aluminum are included in this overview as well, as they show strong similarities in their reactivity and mechanistic pathways to aforementioned early transition metals. While the structure-reactivity principles are well understood for certain hydroamination processes, e.g., in the intramolecular hydroamination of aminoalkenes or the intermolecular hydroamination of alkynes, other transformations, in particular the intermolecular hydroamination of alkenes, remain highly challenging. Due to the potential of the hydroamination process for the synthesis of pharmaceuticals and other industrially relevant fine chemicals, a strong emphasis is given on the application of chiral catalysts in stereoselective processes.

5. Late Transition Metal-Catalyzed Hydroamination

   Naoko Nishina, Yoshinori Yamamoto

   Abstract

   This chapter describes late transition metal complexes-catalyzed hydroamination, the formal addition of an H–N bond across a C–C multiple bond. Late transition metal catalysis has been intensely developed in the hydroamination and additions of various kinds of amines to C–C multiple bonds have been achieved. The reaction pathways strongly depend on the choice of metal complexes, substrates, and reaction conditions. This chapter is organized primarily based on the difference in the mechanisms of hydroamination reactions, and in the scope section concise summary of the hydroamination reaction is shown.

6. Chiral Metal Complex-Promoted Asymmetric Hydrophosphinations

   Sumod A. Pullarkat, Pak-Hing Leung

   Abstract

   This chapter provides an account of the synthesis of a series of chiral tertiary phosphines via the metal complex-assisted asymmetric hydrophosphination methodology which involves secondary phosphines as the nucleophiles. Chiral aza- and phosphapalladacycles are found to function as highly efficient templates or catalysts for the asymmetric P–H addition reaction. The versatile protocol allows for the asymmetric hydrophosphination of olefinic C=C bonds of monophosphines thus yielding a family of tertiary C*-diphosphines as well as C*P*-diphosphines, depending on the nucleophile employed. The addition of two equivalents of HPPh₂ to symmetrical bifunctionalized alkynes leading to generation of two new C* centers is also supported. The air-sensitive nucleophiles and the unsaturated substrates containing unprotected functionalities such as aldehyde, keto, ester, cyano, and alcohol can be utilized directly under this mild and facile reaction conditions. The methodology is equally efficient when applied to the generation of P–N ligand systems via hydrophosphination of unsaturated pyridyl-based substrates as well as systems with C=N moieties. The protocol has also the added advantage of allowing the selective formation of 1,1-, 1,2-, and 1,3-diphosphines simply by judicious control of reaction conditions. This reaction can also be extended to the synthesis of chiral triphosphine systems. This synthetic strategy therefore promises to be a versatile approach for the generation of a wide range of chiral tertiary phosphine ligands with potential applications in catalysis.

7. Recent Progress in Transition Metal-Catalyzed Addition Reactions of H–P(O) Compounds with Unsaturated Carbon Linkages

   Masato Tanaka

   Abstract

   Organophosphorus compounds are playing important roles in our daily life covering a wide range of applications from medicinal use to flame-retardant materials. Although classical synthetic methodologies are still used to synthesize them, the addition reactions of H–P(O) compounds such as H-phosphonates, H-phosphinates, and sec-phosphine oxides have been developed to partially replace the classical methods and are envisioned to be an indispensable tool in the near future. This chapter intends basically to provide recent progress in the field, but not a full scope on the reaction since the same subject was already written by the author in 2004.

8. Group 8 Metals-Catalyzed O–H Bond Addition to Unsaturated Molecules

   Christian Bruneau

   Abstract

   The formation of carbon–oxygen bond upon addition of O-nucleophiles to unsaturated molecules is very attractive as it represents an atom economical strategy to prepare a variety of saturated compounds from olefins and vinylic derivatives from alkynes. Group 8 metals, especially ruthenium have provided an important contribution in this field. We report here on iron- and ruthenium-catalyzed addition of nucleophiles to unsaturated systems. As additions to alkenes are still scarce with these metals and the use of iron catalysts is limited, the main part of the chapter is dedicated to addition of carbamates, carboxylic acids, alcohols and water to triple bonds with ruthenium catalysts.

9. Groups 9 and 10 Metals-Catalyzed O–H Bond Addition to Unsaturated Molecules

   Giorgio Abbiati, Egle M. Beccalli, Elisabetta Rossi

   Abstract

   Progress in the field of inter- and intramolecular additions of oxygen nucleophiles (water, alcohols, phenols, and carboxylic acids) to alkenes, allenes, alkynes, and nitriles catalyzed by Co, Rh, Ir, Ni, Pd, and Pt is critically reviewed.

10. Gold-Catalyzed O–H Bond Addition to Unsaturated Organic Molecules

    Núria Huguet, Antonio M. Echavarren

    Abstract

    In this chapter, we review the synthetic and mechanistic aspects of addition reactions of water and alcohols to alkynes, alkenes, and allenes in the presence of gold catalysts. In addition, gold-catalyzed hydroxy- and alkoxycyclizations of 1, n-enynes (n = 5–7) are also covered.

11. Transition-Metal-Catalyzed S–H and Se–H Bonds Addition to Unsaturated Molecules

    Akiya Ogawa

    Abstract

    This chapter deals with the transition-metal-catalyzed hydrothiolation and hydroselenation of alkynes and allenes and related unsaturated compounds with thiols and selenols. In these reactions, the regio- and/or stereoselectivities of the addition products can be controlled by switching the transition metal catalysts. Metal sulfides and selenides (RE-ML _n , E = S, Se, M = Ni, Pd, Rh, Zr, Sm, etc.) play an important role as key catalyst species in these hydrothiolation and hydroselenation. The introduction of carbon monoxide into these hydrothiolation and hydroselenation systems leads to novel carbonylation with simultaneous addition of thio and seleno groups to unsaturated bonds.

12. Backmatter