Unsaturated, conjugate amination

If in the reactions of vinyl halides with alkenes a sterically unhindered secondary amine is used as base, different products are obtained (equation 192).6SO Incorporation of the amine occurs to give unsaturated tertiary amine as the major product. The conjugated dienes which would be expected from reaction (191) are present as minor products. 

Lithium naphthalene and sodium naphthalene (11) in solvents such as THF, diglyme, or aliphatic amines were found to be effective agents for the hydrodimerization of isoprene. Although this reaction is not strictly catalytic, it contributes to a better understanding of the base-catalyzed oligomerization of unsaturated conjugated hydrocarbons. 

The Birch reductions of C C double bonds with alkali metals in liquid ammonia or amines obey other rules than do the catalytic hydrogenations (D. Caine, 1976). In these reactions regio- and stereoselectivities are mainly determined by the stabilities of the intermediate carbanions. If one reduces, for example, the a, -unsaturated decalone below with lithium, a dianion is formed, whereof three different conformations (A), (B), and (C) are conceivable. Conformation (A) is the most stable, because repulsion disfavors the cis-decalin system (B) and in (C) the conjugation of the dianion is interrupted. Thus, protonation yields the trans-decalone system (G. Stork, 1964B). 

Ammonia and amines undergo conjugate addition to a 3 unsaturated carbonyl compounds (Section 18 12) On the basis of this information predict the pnncipal organic product of each of the following reactions... 

Both primary and secondary amines add to a /S-unsaturated aldehydes and ketones to yield /3-amino aldehydes and ketones rather than the alternative imines. Under typical reaction conditions, both modes of addition occur rapidly. But because the reactions are reversible, they generally proceed with thermodynamic control rather than kinetic control (Section 14.3), so the more stable conjugate addition product is often obtained to the complete exclusion of the less stable direct addition product. 

The conjugate addition of a carbon nucleophile to an a./3-unsiituratcd acceptor is known as the Michael reaction. The best Michael reactions take place between unusually acidic donors (/3-keto esters or /3-diketones) and unhindered n,/3-unsaturated acceptors. Knamines, prepared by reaction of a ketone with a disu Instituted amine, are also good Michael donors. 

The second chromophore involves another a,g-unsaturated ketone that is in conjugation with an anomalously behaving amide (7). The tertiary amine is responsible for the basic character and the phenolic group is acidic. CTC is fluorescent and can be assayed polarographically (8). 

In a similar manner, polymers with unsaturated chains or side chains can be converted to polyamines [66-69]. Conjugated diolefins usually undergo hydroformylation with low selectivities [70]. Mostly hydrogenation of at least one double bond occurs and mixtures of various saturated and unsaturated amines and diamines are obtained [71]. Similar to alkenes also alkynes may serve as unsaturated compounds in hydro aminomethylation reaction sequences. Although synthetically attractive, only a few investigations towards hydroformylation and hydroaminomethylation of alkynes in the presence of N-nuclcophilcs are known. Usually a preferred transformation to furanonic derivatives is observed under hydroformylation conditions [27]. 

Electrocatalytic hydrogenation has the advantage of milder reaction conditions compared to catalytic hydrogenation. The development of various electrode materials (e.g., massive electrodes, powder cathodes, polymer film electrodes) and the optimization of reaction conditions have led to highly selective electrocatalytic hydrogenations. These are very suitable for the conversion of aliphatic and aromatic nitro compounds to amines and a, fi-unsaturated ketones to saturated ketones. The field is reviewed with 173 references in [158]. While the reduction of conjugated enones does not always proceed chemoselectively at a Hg cathode, the use of a carbon felt electrode coated with polyviologen/Pd particles provided saturated ketones exclusively (Fig. 34) [159]. 

In conjunction with the Knoevenegal reaction, a Michael addition (Figure 22) reaction was also described by Jaekson et al. using the same siliea supported tertiary amines for the catalysis of conjugate addition of nitroalkenes to a,y9-unsaturated carbonyl compounds. At a flow rate of 6.6 pL/min the eonversion rate was constant with a high yield for 7 hours reaction time. 

Preliminary mechanistic studies show no polymerization of the unsaturated aldehydes under Cinchona alkaloid catalysis, thereby indicating that the chiral tertiary amine catalyst does not act as a nucleophilic promoter, similar to Baylis-Hilhnan type reactions (Scheme 1). Rather, the quinuclidine nitrogen acts in a Brpnsted basic deprotonation-activation of various cychc and acyclic 1,3-dicarbonyl donors. The conjugate addition of the 1,3-dicarbonyl donors to a,(3-unsaturated aldehydes generated substrates with aU-carbon quaternary centers in excellent yields and stereoselectivities (Scheme 2) Utility of these aU-carbon quaternary adducts was demonstrated in the seven-step synthesis of (H-)-tanikolide 14, an antifungal metabolite. 

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