Amidation of alkenes

Catalytic hydrocarboxylations and related esterifications as well as amidations of alkenes belong to a family of carbonylation reactions which has attracted considerable industrial interest. Minor changes in the catalyst system as well as in reaction conditions can lead to simple carboxylic acids, diacids, polyketones, or unsaturated acids as products (Scheme 1). Most importantly, these methods provide routes to monocarboxylic acids, e.g., ethylene to propanoic acid (see Section 2.1.2.2), or 1-olefins (readily available from the oligomerization of ethylene discussed in Section 2.3.1.3) to higher carboxylic acids. 

However, Stahl et al. [41] could show that, with the structurally weU-defined pyridinyl oxazoline ligand 34, enantioselective aerobic amidation of alkenes can be achieved for a series of pyrrolidine-forming reactions to 36 from aminoalkenes 35 with up to 98% ee (Scheme 16.8). This regular high enantioselectivity is noteworthy and shows that general enantioselective aza-Wacker chemistry should be a feasible process. 

Since an amide nitrogen is far less basic than that of an aliphatic amine, amides do not displace alkene from palladium. The N atom of an amide is thus able to attack alkenes coordinated to Pd(II) to give vinyl amides, according to Scheme 1. Given in Table 1 is an example of the amidation of alkenes. The amidation can be made catalytic by using a combination of CuCl and O2 in the presence or absence of hexamethylphosphoramide (HMPA). The use of O2 alone also makes the reaction catalytic. The amidation does not proceed well with simple alkenes however, electron-deficient alkenes such as methyl acrylate and vinyl ketones undergo an effective catalytic amidation. Note that cyclic carbamates, because of the higher nucleophilicity of the N atom, are more reactive than cyclic amides. 

Abstract During the last decades a powerful set of protocols featuring C(sp )-N bond formation have emerged as convenient alternatives for the assembly of enamine and enamides. Those methods consist of mostly palladium-catalyzed oxidative amidations of alkenes and both palladium- and copper-catalyzed cross-couplings between generally vinyl halides or pseudohalides and amines or amides. In this review recent advances in both types of processes will be disclosed. Additionally, the synthetic value of the title processes will be illustrated by describing relevant total syntheses of natural products involving vinylation process as the key step. 

Ethers, esters, amides and imidazolidines containing an epithio group are said to be effective in enhancing the antiwear and extreme pressure peiformance of lubricants. Other uses of thiiranes are as follows fuel gas odorant (2-methylthiirane), improvement of antistatic and wetting properties of fibers and films [poly(ethyleneglycol) ethers of 2-hydroxymethyl thiirane], inhibition of alkene metathesis (2-methylthiirane), stabilizers for poly(thiirane) (halogen adducts of thiiranes), enhancement of respiration of tobacco leaves (thiirane), tobacco additives to reduce nicotine and to reduce phenol levels in smoke [2-(methoxymethyl)thiirane], stabilizers for trichloroethylene and 1,1,1-trichloroethane (2-methylthiirane, 2-hydroxymethylthiirane) and stabilizers for organic compounds (0,0-dialkyldithiophosphate esters of 2-mercaptomethylthiirane). The product of the reaction of aniline with thiirane is reported to be useful in the flotation of zinc sulfide. 

Addition of amides to alkenes addition of amines to ketenes... 

The catalytic hydroformylation of alkenes has been extensively studied. The selective formation of linear versus branched aldehydes is of capital relevance, and this selectivity is influenced by many factors such as the configuration of the ligands in the metallic catalysts, i.e., its bite angle, flexibility, and electronic properties [152,153]. A series of phosphinous amide ligands have been developed for influencing the direction of approach of the substrate to the active catalyst and, therefore, on the selectivity of the reaction. The use of Rh(I) catalysts bearing the ligands in Scheme 34, that is the phosphinous amides 37 (R ... 

Geranyl chloride can be prepared from geraniol by the careful use of triphenylphosphine in carbon tetrachloride. Tris(dimethylamino)phosphine reacts with carbon tetrachloride to form the complex (42) which can be used to form the enol esters (43) from acid anhydrides. Similarly, aldehydes form the alkenes (44), and esters or amides of trichloroacetic acid are converted to glycidic esters. ... 

Che et al. have reported that chiral Ru11(salen)s (54a) and (54b) are efficient catalysts for aziridination of alkenes (up to 83% ee) and amidation of silyl enol ethers (up to 97% ee), respectively (Scheme 39).163... 

The ruthenium carbene catalysts 1 developed by Grubbs are distinguished by an exceptional tolerance towards polar functional groups [3]. Although generalizations are difficult and further experimental data are necessary in order to obtain a fully comprehensive picture, some trends may be deduced from the literature reports. Thus, many examples indicate that ethers, silyl ethers, acetals, esters, amides, carbamates, sulfonamides, silanes and various heterocyclic entities do not disturb. Moreover, ketones and even aldehyde functions are compatible, in contrast to reactions catalyzed by the molybdenum alkylidene complex 24 which is known to react with these groups under certain conditions [26]. Even unprotected alcohols and free carboxylic acids seem to be tolerated by 1. It should also be emphasized that the sensitivity of 1 toward the substitution pattern of alkenes outlined above usually leaves pre-existing di-, tri- and tetrasubstituted double bonds in the substrates unaffected. A nice example that illustrates many of these features is the clean dimerization of FK-506 45 to compound 46 reported by Schreiber et al. (Scheme 12) [27]. 

Applications of the cross-metathesis reaction in more diverse areas of organic chemistry are beginning to appear in the literature. For example, the use of alkene metathesis in solution-phase combinatorial synthesis was recently reported by Boger and co-workers [45]. They assembled a chemical library of 600 compounds 27 (including cisttrans isomers) in which the final reaction was the metathesis of a mixture of 24 oo-alkene carboxamides 26 (prepared from six ami-nodiacetamides, with differing amide groups, each functionalised with four to-alkene carboxylic acids) (Eq.27). 

In the hydroxycyclopropanation of alkenes, esters may be more reactive than N,N-dialkylcarboxamides, as is illustrated by the exclusive formation of the disubstituted cyclopropanol 75 from the succinic acid monoester monoamide 73 (Scheme 11.21) [91]. However, the reactivities of both ester- as well as amide-carbonyl groups can be significantly influenced by the steric bulk around them [81,91]. Thus, in intermolecular competitions for reaction with the titanacydopropane intermediate derived from an alkylmagnesium halide and titanium tetraisopropoxide or methyltitanium triisoprop-oxide, between N,N-dibenzylformamide (48) and tert-butyl acetate (76) as well as between N,N-dibenzylacetamide (78) and tert-butyl acetate (76), the amide won in both cases and only the corresponding cyclopropylamines 77 and 79, respectively, were obtained (Scheme 11.21) [62,119]. 

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