Bond forming transformation

Chiral C2-symmetric ansa-metallocenes, also referred to as bridged metallocenes, find extensive use as catalysts that effect asymmetric C—C bond-forming transformations [4]. In general, bridged ethylene(bis(tetrahydroindenyl))zirconocene dichloride ((ebthi)ZrCl2) 1 or its derived binaphtholate ((ebthi)Zrbinol) 2 [5] and related derivatives thereof have been extensively utilized in the development of a variety of catalytic asymmetric alkene alkylations. 

Catalytic olefin metathesis, in only a few years, has risen to be one of the most important and reliable processes in organic synthesis. Recently, several reports by Schrock and Hoveydallsbenantioselective synthesis of exo-brevicomin by Burke utilizes chiral catalyst 91 (Scheme 13) to effect the desymmetriza-tion of 90 through a ring-closing metathesis.11531... 

Also known as Morita-Baylis-Hillman reaction, and occasionally known as Rauhut-Currier reaction. It is a carbon—carbon bond-forming transformation of an electron-poor alkene with a carbon electrophile. Electron-poor alkenes include acrylic esters, acrylonitriles, vinyl ketones, vinyl sulfones, and acroleins. On the other hand, carbon electrophiles may be aldehydes, a-alkoxycarbonyl ketones, aldimines, and Michael acceptors. 

Cascade reactions signify reactions involving two or more bond forming transformations that take place under unchanged reaction conditions and in which the subsequent reactions result from the functionality formed in the previous step5. 

Cyclopropanation reactions are one set in an array of C-C bond-forming transformations attributable to metal carbenes (Scheme 5.1) and are often mistakenly referred to by the nonspecific term carbenoid. Both cyclopropanation and cyclopropenation reactions, as well as the related aromatic cycloaddition process, occur by addition. Ylide formation is an association transformation, and insertion requires no further definition. All of these reactions occur with diazo compounds, preferably those with at least one attached carbonyl group. Several general reviews of diazo compounds and their reactions have been published recently and serve as valuable references to this rapidly expanding field [7-10]. The book by Doyle, McKervey, and Ye [7] provides an intensive and thorough overview of the field through 19% and part of 1997. 

The stereochemical outcome of a photochemical [2 + 2] photocycloaddition depends highly on the approach of the two reactants as well as the sterochemical features of the product(s). In this context stereoselective [2 + 2]-photocycloaddition reactions have emerged as powerful C-C bond forming transformations leading to useful and versatile building blocks [59,60]. Some examples of such reactions are presented below. 

The Ramberg-Backlund reaction, a novel carbon-carbon bond forming transformation, was discovered in 1940 when ethyl chloroethylsulfone 1, upon treatment with NaOH, was shown to form a mixture of cis and trans 2-butene. (Fig. 1) (7).The reaction has been used sporadically over the intervening years and has just received a comprehensive review in 2003.(2-8 )... 

Combining structural diversity and complexity with synthetic efficiency has led to an increased interest in multicomponent domino reactions. A multicomponent reaction is defined as a reaction in which more than two substrates, all present together, react with each other to form a product that is derived from all components in that system. Domino reactions as classified by Tietze [2b] are processes involving two or more bond-forming transformations, which take place under the same... 

Thiazoles and benzothiazoles are suitable partners in the Negishi coupling where typically they have been used as the corresponding nuclophilic zinc halides. 2-Thiazolylzinc halides can be prepared by deprotonation with n-BuLi and treatment of the anion with zinc halide (ZnX2). The examples below illustrate the convenience of such a C-C bonding forming transformation. 

The Michael reaction was one of the most powerful C—C bond-forming transformations. In 2005, Zhai and co-workers [80] reported a unexpected one-step assembly of butyrolactones from benzoins and acrylate via a tandem reaction promoted by NHC 64 (Scheme 7.62). An NHC-promoted Michael addition may involved in this chemical transformation. 

The paramount importance of Michael additions as versatile C-C bond forming transformations was discussed in some detail earlier in this volume. Thus, it is not surprising that, besides the use of chiral PTCs in asymmetric a-alkylation reactions, their use for stereoselective Michael additions is one of the most carefully investigated reactions in asymmetric phase-transfer catalysis (328, 329). Accordingly, the additional use of this methodology in asymmetric total synthesis has been reported on several occasions. 

In spite of the explosive growth of enantioselective organocatalysed domino reactions in the last decade,an increasing number of enantioselective metal-catalysed domino processes have been developed in the last few years. A domino reaction has been defined by Tietze as a reaction which involves two or more bond-forming transformations, taking place under the same reaction conditions, without adding additional reagents and catalysts, and in which the subsequent reactions result as a consequence of the functionality... 

Stereoselective Multiple Bond-Forming Transformations in Organic Synthesis, First Edition. Edited by Jean Rodriguez and Damien Bonne. 

Bonne, D., Constantieux, T., Coquerel, Y., Rodriguez, J. (2013). Stereoselective multiple bond-forming transformations (MBFTs) the power of 1,2- and 1,3-dicarbonyl compounds. Chemistry - A Emopean Jomnal, 19, 2218-2231. 

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