Morpholine piperidine

Recently Stamhuis et al. (33) have determined the base strengths of morpholine, piperidine, and pyrrolidine enamines of isobutyraldehyde in aqueous solutions by kinetic, potentiometric, and spectroscopic methods at 25° and found that these enamines are 200-1000 times weaker bases than the secondary amines from which they are formed and 30-200 times less basic than the corresponding saturated tertiary enamines. The baseweakening effect has been attributed to the electron-withdrawing inductive effect of the double bond and the overlap of the electron pair on the nitrogen atom with the tt electrons of the double bond. It was pointed out that the kinetic protonation in the hydrolysis of these enamines occurs at the nitrogen atom, whereas the protonation under thermodynamic control takes place at the -carbon atom, which is, however, dependent upon the pH of the solution (84,85). The measurement of base strengths of enamines in chloroform solution show that they are 10-30 times weaker bases than the secondary amines from which they are derived (4,86). 

Experiments designed to clarify the situation were carried out by Wittig and Mayer (40). It was shown that changing the molar ratio of amine (diethylamine, di- -butylamine, or diisobutylamine) to -butyraldehyde from 1 1 to 2 1 did not affect the yield of enamine (53- 64%, based on the aldehyde). Contrariwise, changing the ratio of amine (morpholine, piperidine, or pyrrolidine) to n-butyraldehyde from 1 1 to 2 1 boosted the yields from 52-57 % to 80-85 %. The authors interpret these data as indicating that the cyclic amines form aminals with n-butyraldehyde, while the open-chain do not. Infrared evidence is stated as having shown that the aminal originates not from attack of excess amine on the enamine, which is stable under the conditions of the reaction, but from the N-hemiacetal (17). 

Complexes 92 and 93 also show good activity for the hydroamination of methacrylonitrile with morpholine, piperidine or A -methylpiperazine (70-93% conversion at 2.5 mol%, 90°C in 24 h) [80]. 

Poupin P, Godon JJ, Zumstein E, Truffant N (1999) Degradation of morpholine, piperidine and pyrrolidine by microbacteria evidence for the involvement of a cytochrome P450. Can J Microbiol 45 209-216... 

Reaction of l-aryl-3-carbethoxy-6-phenyl-l,4,5,6-tetrahydropyridazin-4-ones 718 with activated olefins such as benzalacetophenone, benzalacetone, 3-benzylideneacetylacetone, diethyl 2-benzylidenemalonate, and a-cyano-/3-phenylacrylic acid in the presence of an organic base like pyrrolidine, morpholine, piperidine, or triethylamine gave the corresponding 2,8-dihydro-l//-pyrano[2,3-t7 pyridazines 719-723, respectively. The 1-oxo- and 1-imino derivatives of the pyrano[2,3-r/ pyridazine ring system were also prepared from the respective 6-oxo or 6-imino derivative of the starting pyridazine 718 under the same conditions (Equation 60) <1989IJB733>. 

The amine used to make enamine is usually pyrrolidine, morpholine, piperidine or diethylamine. 

The reaction of norbomadiene and secondary amines (morpholine, piperidine, pyrrolidine, N- methylbutylamine) results in the formation of interesting aminated products 593... 

Morpholine, piperidine and diethylamine were used as bases. The catalyst precursor was [Pd(OAc)2] (106) and P(o-tol)3 or a similar phosphine. The mechanism is thought to involve vinylation of the alkene as in Scheme 74 as the initial process. This leads to the formation of an i73-allylpalladium derivative, which is then trapped by the amine to give the final product. If dienes are used instead of monoenes, 2,5-dienylamines are produced (equation 193).651... 

Starting from 2-amino-3-cyano-4,5-dihydrothiophenes 60 the derived 2-benzamido derivatives 61 were treated with cyclohexylamine, morpholine, piperidine, or pyrrolidine to yield the respective 5,6-dihydro-2-phenyl 4-substituted aminothieno[2,3-d]pyrimidines 62a-d (83CPB401). In the presence of tin(IV) chloride, benzamides 61 reacted with acetic (or propionic) anhydride to give the corresponding 3-acetyl(or propionyl)thieno[2,3-[Pg.206]

RuCl2(PMe3)(C6Me6) and RuCl2(PMe3)(p-cymene) appear to be much more efficient catalysts than other mononuclear ruthenium complexes, or Ru3(CO)12, for a variety of secondary amines and terminal alkynes, such as diethylamine, morpholine, piperidine, and pyrrolidine (65,201), except for acetylene itself (202,203). The regioselective addition to the terminal carbon suggests that that the reaction proceeds via an arene ruthenium vinyl-idene intermediate that has been characterized (66) (Section II,A,3,d). 

Dibenzoyl peroxide oxidizes morpholine, piperidine and other simple secondary amines in good yield to the corresponding benzoyloxyamines these compounds can then be hydrolyzed in basic conditions to the free hydroxylamines. An analogous reaction t es place between secondary amines and bis(diphe-nylphosphinyl) peroxide for example, diethylamine is converted into the hydroxylamine derivative Et2NOFOPh2 (97%) by this reagent. The products are easily hydrolyzed to the free hydroxylamines, and they can also be used as aminating agents. 

The use of cyclic enamines" > " " b.436,441,443,446.447, 456.457,470-480 (-g g UQ o ) or dieneamines (e.g., 141 ) yields fused bicyclic systems, although the latter may also yield bis-thietane sulfones. Enamines derived from morpholine, piperidine, pyrrolidine, and dimethylamine are most commonly used, but derivatives of diethylamine, di- -propyl-amine, piperazine, 4-benzylpiperidine, methylpyrrolidines, hexahydroazepin, N-methylaniline, and indoline have also been treated with sulfenes to give thietane sulfones. Asymmetric induction has been observed with the optically active enamine, 142. ... 

Enamines. Review of the formation and uses of enamines. Of the three amines most commonly used for formation of enamines (morpholine, piperidine, pyrrolidine), pyrrolidine is the most reactive. ... 

Meldrum s acid is best introduced into a bicyclo[n.l. OJalkylamine system by its reaction with bicyclic A,0-acetals. Various amines such as morpholine, piperidine, pyrrolidine, dimethylamine, benzylamine, or azepane can be used for this reaction with c/j-bicyclic systems. Azepane as amino component is essential for the analogous reaction of a trans-bi-cyclo[9.1.0]dodecanone A,0-acetal. Both cw-bicyclo[n.l.0]alkane isomers 5 possessing Meldrum s acid either in the exo-position or in the enrfo-position were synthesized as sterically... 

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