Amine-acids => alkenes

Entries 5 to 7 are examples of oxidation of boranes to the carbonyl level. In Entry 5, chromic acid was used to obtain a ketone. Entry 6 shows 5 mol % tetrapropylam-monium perruthenate with Af-methylmorpholine-lV-oxide as the stoichiometric oxidant converting the borane directly to a ketone. Aldehydes were obtained from terminal alkenes using this reagent combination. Pyridinium chlorochromate (Entry 7) can also be used to obtain aldehydes. Entries 8 and 9 illustrate methods for amination of alkenes via boranes. Entries 10 and 11 illustrate the preparation of halides. 

Vinylamines (enamines) are reduced by alane, mono- and dichloroalane to saturated amines, and hydrogenolyzed to amines and alkenes [710]. Reduction is favored by dichloroalane while hydrogenolysis is favored by alane. Alane, chloroalane and dichloroalane gave the following results with -N-pyrrolidinylcyclohexene V-pyrrolidinylcyclohexane in 13, 15 and 22% yield, and pyrrolidine and cyclohexene in 80, 75 and 75% yields, respectively [710]. Saturated amines were also obtained by treatment of enamines with sodium borohydride [711], with sodium cyanoborohydride [103, 712] (Procedure 22, p. 210) and by heating for 1-2 hours at 50-70° with 87% or 9S% formic acid (yields 37-89%) [320]. 

Sulfonylhydroxylamines and hydroxylamine O-sulfonic acid have found wide apph-cation in synthesis of amines from achiral or chiral organoboranes and boronate esters and the hydroboration-amination methodology is successfully used for direct amination of alkenes. 0-Sulfonyloximes were also found to be good reagents for synthesis of amines from organomagnesium, -copper and -zinc reagents. 

The latter transformation requires the use of a small amount of an acid or its ammonium salt. By using [Cp2TiMe2] as the catalyst, primary anilines as well as steri-cally hindered tert-alkyl- and sec-alkylamines can be reacted.596 Hydroamination with sterically less hindered amines are very slow. This was explained by a mechanism in which equlibrium between the catalytically active [L1L2Ti=NR] imido complex and ist dimer for sterically hindered amines favors a fast reaction. Lantha-nade metallocenes catalyze the regiospecific addition of primary amines to alkenes, dienes, and alkynes.598 The rates, however, are several orders of magnitude lower than those of the corresponding intramolecular additions. 

Unsaturated hydrocarbons (alkenes, dienes) react with carbon monoxide and a proton source (H20, alcohols, amines, acids) under strong acidic conditions to form carboxylic acids or carboxylic acid derivatives. Since a carbocationic mechanism is operative, not only alkenes but also other compounds that can serve as the carbocation source (alcohols, saturated hydrocarbons) can be carboxylated. Metal catalysts can also effect the carboxylation of alkenes, dienes, alkynes, and alcohols. 

The order of reactivities of various functional groups determined under standard conditions (using externally generated diborane, and tetrahydrofuran as solvent) is acid > alkene > ketone > nitrile > epoxide > ester > acid chloride.33 Acids, aldehydes, ketones, epoxides, nitriles, lactones and azo compounds are reduced rapidly, esters more slowly and chloral, acid chlorides and nitro compounds are inert. Double bonds undergo the hydroboration reaction,25 nitriles and azo compounds are reduced to amines, and the remaining groups to alcohols. Ketones can be reduced selectively in the presence of epoxides. Contrary to the order of reactivities given above, it has been claimed that nitriles are reduced more rapidly than ketones.223... 

The hydrocarboxylation reaction of alkenes and alkynes is one which utilizes carbon monoxide to produce carboxylic acid derivatives. The source of hydrogen is a protic solvent (equation 35) dihydrogen is not usually added to the reaction. There are a number of variations to this reaction, since the solvent can be water, alcohols, amines, acids, etc. The catalysts can be Group VIII-X transition metals, but cobalt, rhodium, nickel, palladium and platinum have found the most use. 

Quach and Batey299 reported the coupling of primary amines with phenylboronic acids catalyzed by Cu(OAc)2 (10 mol%) without base or ligand but in the presence of 4 A molecular sieves and air in CH2C12 solvent (equation 73). Reactions of potassium phenyl-trifluoroborate also occurred, but in lower yields than reactions of boronic acids. They showed that these reactions occur with a variety of functional groups on the amine, including alkenes, esters, ketones and ketals. a-Amino acid derivatives underwent reaction without detectable epimerization. Anilines were poorer cross-coupling partners under these conditions than were primary and secondary cyclic aliphatic amines. 

Reductions. The reagent is useful for reduction of many bifunctional compounds containing ester groups in refluxing chloroform. Amides and imines give amines, acids and alkenes afford alcohols. 

The relevant literature in this subfield is too voluminous to be detailed here. Overviews are available [62], and only a few recent references to the newest publications are given below. Oxidations of the following types have been performed alcohol - ketone [63] aldehyde —> acid alkene —> diol or epoxide [64-67] al-kene - aldehyde, acid 1-alkyne —> ketoaldehyde and acid (1 C-atom shorter) internal alkyne —> a,/3-epoxyketone vic-diol —> 1,2-diketone [68] or hydroxyketone [69] amine —> amine oxide [70] aromatic amine —> nitrosobenzene, nitrobenzene, azoxybenzene [71]. 

The aminometallation reaction is of special relevance to the key step involved in metal-catalyzed amination of alkenes and alkynes [4b,d,41]. The reversible attack of aliphatic amines at the monoalkene ligand shown in Eq. 8.6 may proceed in stereospecific trans addition and elimination [42]. For example, diethylamine was reacted with 1-butene, which coordinated to Pt using only one enantioface of the olefin ((S)-l-butene-Pt bond) (Scheme 8.24) [42a]. Alkylplatinum complex thus formed was subjected to acidic work-up to give optically active amine salt having the S-configuration at the asymmetric carbon. This result unambiguously demon-... 

Reactive amines other than ammonia have also been employed to distinguish Bronsted acid sites in various zeolites using a combination of TPD and thermo-gravimetric analysis (TGA) techniques [135]. The method is based on the fact that surface Bronsted sites may induce thermal decomposition of aliphatic amines to alkenes and ammonia over a narrow temperature range. The number of amine molecules reacted is equated to the number of strong Bronsted acid sites. By choosing amines of appropriate sizes it is possible to discriminate between acid sites located in pores of different diameters. 

The RUO4 catalytic system oxidizes secondary alcohols to ketones and primary alcohols to carboxylic acids. Alkenes can be oxidized completely, to produce the corresponding carbonyl compounds, or partially, to produce epoxides this transformation will be discussed below. In addition, methylene carbons adjacent to certain functional groups can be oxidized to the corresponding carbonyl ethers are converted to esters, tertiary amines and amides to amides and imides. 

The hydrohydrazination represented a general solution for the amination of alkenes, but the protected hydrazines obtained are sometimes difficult to transform to the free amines. At this point, we turned to sulfonyl azides as nitrogen sources, based on then-capacity to react both with enolates and carbon-centered radicals. Mechanistic investigations of the hydrohydrazination reaction had suggested a radical character for the formed organocobalt intermediate. " We were pleased to see that the Cobalt-catalyst 4 was able to promote the hydroazidation of 4-phenylbut-l-ene (3) with ethanesulfonyl azide (7), giving the product derived from the formal Markovnikov addition of hydrazoic acid onto the C-C double bond exclusively, albeit in moderate yields (50%). 

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