Amines allenic

Heating compounds containing the system C C—C—S—C=C in hexa-methylphosphoramide (HMPA) gives 2if-thiopyrans (247). Isomeric thio-phens appear when the reaction is conducted in the presence of amines. Allene sulphoxides (248) are readily available by reaction of alkynols with sulphenyl chlorides to form labile sulphenyl esters, which rearrange to (248). The two chiral centres in these molecules (sulphoxide and allene) result in... 

Note 2. The further conversion into the yneamine CH3CEC-Morph is stopped almost completely by the addition of HO-tert.-Ci,Hg which forms the 1 1 complex with KO-tert.-CgHg. If the isomerization with KO-tert.-CgHg is carried out in DMSO, an equilibrium mixture of about 80 of the allenic amine and 20% of the yneamine is formed after 1-2 min at 30°C. 

When allene derivatives are treated with aryl halides in the presence of Pd(0), the aryl group is introduced to the central carbon by insertion of one of the allenic bonds to form the 7r-allylpalladium intermediate 271, which is attacked further by amine to give the allylic amine 272. A good ligand for the reaction is dppe[182]. Intramolecular reaction of the 7-aminoallene 273 affords the pyrrolidine derivative 274[183]. 

Like butadiene, allene undergoes dimerization and addition of nucleophiles to give 1-substituted 3-methyl-2-methylene-3-butenyl compounds. Dimerization-hydration of allene is catalyzed by Pd(0) in the presence of CO2 to give 3-methyl-2-methylene-3-buten-l-ol (1). An addition reaction with. MleOH proceeds without CO2 to give 2-methyl-4-methoxy-3-inethylene-1-butene (2)[1]. Similarly, piperidine reacts with allene to give the dimeric amine 3, and the reaction of malonate affords 4 in good yields. Pd(0) coordinated by maleic anhydride (MA) IS used as a catalyst[2]. 

The addition of secondary amines to acetylenes is most applicable to the synthesis of conjugated acyclic enamines (50,171,172). Particularly the addition to acetylenic esters and sulfones has been investigated (173-177) and it appears that an initial trans addition is followed by isomerization to more stable products where the amine and functional group are in a trans orientation (178). Enamines have also been obtained by addition of secondary amines to allenes (179). 

An increased hydrogen ion concentration, that is a considerably greater amount of acid than the theoretical two equivalents of Scheme 2-1, is necessary in the diazotization of weakly basic amines. The classic example of this is the preparation of 4-nitrobenzenediazonium ions 4-nitroaniline is dissolved in hot 5-10 m HC1 to convert it into the anilinium ion and the solution is either cooled quickly or poured onto ice. In this way the anilinium chloride is precipitated before hydrolysis to the base can occur. On immediate addition of nitrite, smooth diazotization can be obtained. The diazonium salt solution formed should be practically clear and should not become cloudy on standing in the dark. Some practice is necessary, and details can be found in the books emphasizing preparative aspects (Fierz-David and Blangey, 1952 Saunders and Allen, 1985 in Houben-Weyl, Vol. E 16a, Part II, the chapter written by Engel, 1990). These books give a series of detailed prescriptions for specific examples and a useful review of the principal variations of the methods of diazotization. Such reviews have also been written by Putter (1965) and Schank (1975). 

Conjugate addition of chiral amines to allenic and acetylenic sulfones has been reported73. The reaction 112 with (—)-ephedrine gives only one of the two possible diastereomeric oxazolines in high yield (equation 89). 

Since 3-methylenecyclobutane-l,2-dicarboxylic anhydride is easily converted to 3-methyl-2-cydobutene-l,2-dicarboxylic acid, it is an intermediate to a variety of cyclobutenes. The dimethyl ester of 3-methylenecyclobutane-l,2-dicarboxylic acid is also a versatile compound on pyrolysis it gives the substituted allene, methyl butadienoate, and on treatment with amines it gives a cyclobutene, dimethyl 3-methyl-2-cyclobutene-l,2-di-carboxylate. ... 

Allene, l,3-di-ferf-butyl-l,3-dicyano- [2,3-Pentadienedimtnle, 2,4-bis(l,l-di-methylethyl) ], 55, 38 ALLYL ALCOHOL [2 Propen 1 ol], 55, 1 Amberhte IRA-400, 55, 5 Amine, diethyl- [Ethanamme, IV-ethyl-],... 

Secondary amines can be added to certain nonactivated alkenes if palladium(II) complexes are used as catalysts The complexation lowers the electron density of the double bond, facilitating nucleophilic attack. Markovnikov orientation is observed and the addition is anti An intramolecular addition to an alkyne unit in the presence of a palladium compound, generated a tetrahydropyridine, and a related addition to an allene is known.Amines add to allenes in the presence of a catalytic amount of CuBr " or palladium compounds.Molybdenum complexes have also been used in the addition of aniline to alkenes. Reduction of nitro compounds in the presence of rhodium catalysts, in the presence of alkenes, CO and H2, leads to an amine unit adding to the alkene moiety. An intramolecular addition of an amine unit to an alkene to form a pyrrolidine was reported using a lanthanide reagent. 

The groups R2N and Cl can be added directly to alkenes, allenes, conjugated dienes, and alkynes, by treatment with dialkyl-V-chloroamines and acids. " These are free-radical additions, with initial attack by the R2NH- radical ion. " N-Halo amides (RCONHX) add RCONH and X to double bonds under the influence of UV light or chromous chloride. " Amines add to allenes in the presence of a palladium catalyst. ... 

Cyclization of allene 71 using a catalyst system comprising 10 mol % Pd(OAc)2, 20 mol % PPhj and K COj in the presence of amine 72 affords isoquinolone 73 <95CC1903>. 

The polymerization of allenes by [Rh(CO)2Cl]2 and a ligand (phosphines, arsines, amines, isocyanides) (175) and the polymerization of cyclohexyl isocyanide by Co2(CO)g (173) have been reported. 

Hydroaminomethylahon of alkenes [path (c)j wiU not be considered [12]. This review deals exclusively with the hydroaminahon reaction [path (d)], i.e. the direct addition of the N-H bond of NH3 or amines across unsaturated carbon-carbon bonds. It is devoted to the state of the art for the catalytic hydroamination of alkenes and styrenes but also of alkynes, 1,3-dienes and allenes, with no mention of activated substrates (such as Michael acceptors) for which the hydroamination occurs without catalysts. Similarly, the reachon of the N-H bond of amine derivatives such as carboxamides, tosylamides, ureas, etc. will not be considered. 

An analogous catalytic system has been applied to the IH of y- and 5-allenic amines which cyclize smoothly in the 5-Exo-Trig or 6-Exo-Trig mode, giving vinylpyrrolidines and vinylpiperidines, respectively (Eq. 4.92) [313]. 

IH of allenic amines also occurs in the presence of silver salts. IH of a-allenic amines proceeds in good yields in the presence of AgBp4 and provides a useful method for 3-pyrrolines synthesis via Endo-Trig processes (Eq. 4.93) [314]. 

Although less efficient (TOP = 0.04 h ), similar IH ofofy- and 5-allenic amines in the presence of AgNOj give 2-alkenylpyrrolidines and 2-alkenylpiperidines, respectively (5 [or 6]-Exo-Trig processes) [315]. These reactions have been applied to the synthesis of ( )-pinidine [316] and -) R) coniine [317]. 

The [(T -C3H5)PdCl]2/dppf/AcOH catalytic system has been used for the bis(hy-droamination) of 3-alken-l-ynes to alkenic 1,4-diamines (Eq. 4.94), a reaction which seems to be mechanistically related to the hydroamination of allenes since an a-al-lenic amine CH2=C=CH(R )CH2NR2 is believed to be an intermediate [318]. 

A Pd(0) /benzoic acid system has been found to catalyze the hydroamination of certain arylalkynes with secondary amines, a reaction which is also mechanistically related to the hydroamination of allenes, affording high yields of aUyhc amines (Eq. 4.95) [319]. 

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