Other Related Reactions

Using 186b 48% yield, 95% ee Using 191b 88% yield, 97% ee 

C2 substitution makes the — quinoline N atom sterically hindered 

In recent decades, chemists have demonstrated the proficiency of organo-catalysis as a useful synthetic tool for obtaining enantioenriched compounds. Thus, asymmetric organocatalysis has become a field of central importance along with biocatalysis and metal-mediated catalysis. In this chapter, we discuss the tremendous progress that has been achieved in the design and synthesis of various chiral 2-substituted pyrrolidine 

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Desulfurization of /1-ketosulfoxides with Zn/AcOH134 or aluminium amalgam133 can lead to the corresponding ketones. Other related reactions may be those shown in Scheme 3146 147. 

In this section, the reactivities of organosilicon compounds for the Friedel-Crafts alkylation of aromatic compounds in the presence of aluminum chloride catalyst and the mechanism of the alkylation reactions will be discus.sed, along with the orientation and isomer distribution in the products and associated problems such as the decomposition of chloroalkylsilanes to chlorosilanes.. Side reactions such as transalkylation and reorientation of alkylated products will also be mentioned, and the insertion reaction of allylsilylation and other related reactions will be explained. 

In addition to the reaction shown in Scheme 53, some other related reactions that are thought to proceed via cyclic carbometallation have also been reported (Scheme 54). In the cyclization reaction of 2-ethenyl-2 -ethynylbiphenyl, both Cr and W carbyne complexes must undergo the same cyclic carbometallation as that shown in Scheme 53 to give the corresponding metallacyclohexadiene intermediates, but the final products obtained were different.256 Some tungsten-carbyne complexes have been shown to undergo a stepwise [2 + 2 + 2]-cyclization via formal cyclic carbometallation that can be followed by reductive elimination to produce cyclopentadiene-tungsten complexes.2... 

The importance of Hess s law lies in its ability to access information about a reaction that may be difficult (or impossible) to obtain experimentally, by looking at a series of other, related reactions. 

On the other hand, H.B. Henbest realised that adjacent polar functional groups have a directing effect on the epoxidation of alkenes as well as on other related reactions [2]. A very well known example is the 5yn-directing effect of an ally lie hydroxyl group in epoxidations of cyclic alkenes (Scheme 10.1) ... 

Other related reactions involve TV-fluorenylmethyloxycarbonyl (N-Fmoc) AAs and aliphatic aldehydes (83JOC77) or substituted /-butoxycarbonyl (N-Boc) Aas and 2,2-dimethyoxypropane (acetone dimethyl ketal) (84TL5855 87JOC2361 88TL2019), as well as A-(dimethylthio)methylene derivatives of an AA and aromatic aldehydes [89JCS(P1)1577]. 

Other Related Reactions In addition to simple 1,4-addition reactions described so far, other related rhodium-catalyzed asymmetric carbon-carbon bond-forming processes have also been developed. Lautens reported an asymmetric ring-opening of... 

Negishi, E. L, de Meijere, A., Eds. Palladium-Catalyzed Carbonylation and Other Related Reactions Involving Migratory Insertion. In Handbook of Organopalladium Chemistry for Organic Synthesis-, Wiley-Interscience New York, 2002 Vol. 2, pp 2309-2714. 

The thiazolium salt 3-benzyl-5-(2-hydroxyethyl)-4-methyl-l,3-thiazolium chloride is an excellent catalyst for the addition of unsaturated aliphatic aldehydes to vinylketones (79CB84). The presence of a base such as sodium acetate or triethylamine is required, for the thiazolium salt must first be transformed into the ylide structure (615), which then exerts a catalytic effect resembling that of cyanide ion in the benzoin condensation (Scheme 137). Yields of 1,4-diketones (616) produced in this process were generally good. The use of thiazolium salts for other related reactions has been reviewed (76AG(E)639). 

Organometallic methods, with the possible exception of those involving the stoichiometric generation of enolates and other stabilized carbanionic species 140], have seldom been used in carbohydrate chemistry for the synthesis of cyclohexane and cyclopentane derivatives. The present discussion will not cover these areas. The earliest of the examples using a catalytic transition metal appears in the work of Trost and Runge [41], who reported the Pd-catalyzed transformation of the mannose-derived intermediate 22 to the functionalized cyclopentane 23 in 98% yield (Scheme 10). Under a different set of conditions, the same substrate gives a cycloheptenone 24. Other related reactions are the catalytic versions of the Ferrier protocol for the conversion of methylene sugars to cyclohexanones (see Chap. 26) [40,42,43]. 

Epoxides are generally very susceptible to attack by sulfur nucleophiles, in accordance with the recognized nucleophilicity of these reagents.1 The direction of ring fission is governed by the same electronic and stereochemical principles as those operating in other related reactions, e.p. the additions of hydroxylic nucleophiles discussed in section IV.4.A. 

Other related reactions with the heterocyclic or seven-membered rings consist in... 

Cyclization to carbonyl groups by sp3 or sp2 carbon-centered radicals and other related reactions... 

We present here a brief account of the specific dimerization, and other related, reactions undergone by a variety of purine and pyrimidine derivatives, and a number of related compound s, during the course of their electrochemical reduction at the surface of a mercury electrode. A characteristic feature of these reactions is the transfer of an electron to the compound, accompanied, or preceded, by its protonation. The resultant free radicals, generated by a one-electron reduction process, rapidly dimerize to products in which each of the monomeric components possesses an additional electron and an additional proton, relative to the parent monomer1 7). (See Scheme 1)... 

In this chapter, we present the contributions of computational chemistry toward understanding the mechanism and chemistry for three reactions involving nucleophilic attack. The 8 2 reaction, with emphasis on the gas versus solution phase, is presented first Next we describe the critical contribution that computational chemists made in developing the theory of asymmetric induction at carbonyl and vinyl compounds. The chapter concludes with a discussion on the collaborative efforts of synthetic and computational chemists in developing organic catalysts, especially proline and proline-related molecules, for the aldol, Mannich and Michael reaction, and other related reactions. 

Other related reactions of these high-valent species include cyclopropanation of alkenes, oxidation of benzyltrialkylstannanes, dehydration of aldoximes, and olefination of aldehydes and ketones. Mechanisms... 

Other related reactions are the substitutions of aliphatic sulfonate esters by arenes and the epoxide-opening with benzenes catalyzed by gold. In both cases, the aryl groups are the nucleophiles that attack the gold-coordinated sulfonate esters or epoxides, respectively. 

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