Categories: C-N Bond Formation > Amines >
Synthesis of secondary and tertiary amines
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Name Reactions
Reactions
Reductive Amination
Recent Literature
Microwave heating enables a Borrowing Hydrogen strategy to form C-N bonds from
alcohols and amines, removes the need for solvent and reduces the reaction times,
while the results are comparable with those using thermal heating.
A. J. A. Watson, A. C. Maxwell, J. M. J. Williams, J. Org. Chem., 2011,
76, 2328-2331.
A one-pot two-step sequence involving an oxidation/imine-iminium formation/reduction
allowed the N-alkylation of amines by alcohols. Optically active alcohols
and amines can be converted without any epimerization.
C. Guérin, V. Bellosta, G. Guillamot, J. Cossy, Org. Lett., 2011,
13, 3478-3481.
Using 0.5 mol % [Ru(p-cymene)Cl2]2 with the bidentate
phosphines dppf or DPEphos as the catalyst, primary amines have been converted
into secondary amines, and secondary amines into tertiary amines. N-Heterocyclization
reactions of primary amines have been achieved, as well as alkylation reactions
of primary sulfonamides.
M. H. S. A. Hamid, C. L. Allen, G. W. Lamb, A. C. Maxwell, H. C. Maytum, A. J.
A. Watson, J. M. J. Williams, J. Am. Chem. Soc., 2009,
131, 1766-1774.
An efficient, environmentally benign and practical one-pot reductive tandem
mono-N-alkylation of both aromatic and aliphatic azides using dialkylboron
triflates as alkylating agents enables the syntheses of various secondary alkyl
as well as aryl amines, including the synthesis of N10-butylated
pyrrolo[2,1-c][1,4]benzodiazepine-5,11-diones via in situ azido
reductive-cyclization process.
N. Shankaraiah, N. Markandeya, V. Srinivasulu, K. Sreekanth, C. S. Reddy, L. S.
Santos, A. Kamal, J. Org. Chem., 2011,
76, 7017-7026.
Manganese dioxide is employed as an in situ oxidant for the one-pot conversion
of alcohols into imines. In combination with polymer-supported cyanoborohydride
(PSCBH), a one-pot oxidation-imine formation-reduction sequence enables alcohols
to be converted directly into both secondary and tertiary amines.
L. Blackburn, R. J. K. Taylor, Org.
Lett., 2001, 3, 1637-1639.
(Cyanomethyl)phosphonium iodides are easy to prepare and to handle. These
reagents efficiently promote the direct, intermolecular N-alkylation of
amines with alcohols.
F. Zaragoza, H. Stephensen, J. Org. Chem, 2001,
66, 2518-2521.
A method for highly selective anti-Markovnikov hydroamination of terminal
alkenes involves hydroboration of the alkene followed by a novel electrophilic
amination of the alkyl borane catalyzed by an NHC-Cu complex. Terminal alkenes
are successfully transformed into tertiary alkyl amines in the presence of a
variety of functional groups in very good yields ranging with excellent
regioselectivity.
R. P. Rucker, A. M. Whittaker, H. Dang, G. Lalic, J. Am. Chem. Soc., 2012,
134, 6571-6574.
A new synthetic method for the preparation of potassium
organotrifluoroborates through nucleophilic substitution of potassium bromo-
and iodomethyltrifluoroborates is described. Potassium
halomethyltrifluoroborates have been prepared via in situ reaction of n-BuLi
with dibromo- and diiodomethane, respectively, in the presence of trialkyl
borates, followed by treatment with KHF2.
G. A. Molander, J. Ham, Org. Lett.,
2006,
8, 2031-2034.
A copper-catalyzed electrophilic amination of simple and functionalized aryl,
heteroaryl-, benzyl, n-alkyl, sec-alkyl, and tert-alkyl
diorganozinc nucleophiles with R2NOC(O)Ph and RHNOC(O)Ph reagents
as electrophilic nitrogen sources provides tertiary and secondary amines,
respectively, in generally good yields. In many cases, the product may be
isolated analytically pure after a simple extractive workup. A Cu-catalyzed
amination of Grignard reagents using cocatalysis by ZnCl2 is
described.
A. M. Berman, J. S. Johnson, J. Org. Chem.,
2006,
71, 219-224.
Selective mono-N-alkylation of 3-amino alcohols relies on formation
of a stable chelate with 9-BBN. Three prototypical amino alcohols featuring
various bridging units led selectively to the monoalkylated derivatives in
very high yields.
G. Bar-Haim, M. Kol, Org. Lett., 2004, 6, 3549-3551.
A
wide range of chiral propargylamines can be prepared in a one-pot
three-component reaction between an alkyne, an aldehyde and a secondary
amine at room temperature in the presence of CuBr and (R)-quinap in
good yield and good enantioselectivity.
N. Gommermann, C. Koradin, K. Polborn, P. Knochel, Angew. Chem., 2003,
115, 5941-5944.
An efficient palladium-catalyzed asymmetric amination of 2,3-allenyl
phosphates with nitrogen nucleophiles such as amines, hydroxylamines, and
imides can be performed in presence of SEGPHOS or MeOBIPHEP ligand,
affording the corresponding optically active 1-aminated derivatives with
high enantiomeric excess.
Y. Imada, M. Nishida, K. Kutsuwa, S.-I. Murahashi, T. Naota, Org. Lett.,
2005,
7, 5837-5839.
An aryloxotitanium complex is a highly chemo- and regioselective catalyst for
intermolecular hydroamination of terminal alkynes. Branched imines are obtained
in good yield with various primary aromatic and aliphatic amines.
V. Khedkar, A. Tillak, M. Beller, Org. Lett., 2003, 5,
4767-4770.
A polymer-bound, triphenylphosphine-supported reagent allows a one-pot, two-step
synthesis of secondary amines from the corresponding azide and a reactive alkyl
halide.
S. Ayesa, B. Samuelsson, B. Classon, Synlett, 2008,
89-93.
β-Piperidinoethylsulfides can be oxidized by m-chloroperbenzoic acid to
intermediates containing both N-oxide and sulfone functions. These
undergo a Cope-type elimination to a vinylsulfone that can be captured by amines
to afford β-aminoethylsulfones. The synthetic methodology developed can be
utilized in multiple-parallel format and has numerous potential applications in
medicinal chemistry.
R. J. Gruffin, A. Henderson, N. J. Curtin, A. Echalier, J. A. Endicott, I. R.
Hardcastle, D. R. Newell, M. E. M. Noble, L.-Z. Wang, B. T. Golding, J. Am. Chem. Soc., 2006,
128, 6012-6013.
