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.
A catalytic amount of manganese dioxide and solvent-free conditions under air enabled a practical and efficient N-alkylation method for a variety of sulfonamides and amines using alcohols as green alkylating reagents.
X. Yu, C. Liu, L. Jiang, Q. Xu, Org. Lett., 2011, 13, 6184-6187.
N-Heterocyclic carbenes catalyze the oxidation of unactivated aldehydes to esters with manganese(IV) oxide in excellent yield under mild conditions. The reaction proceeds through a transient activated alcohol generated in situ and preserves stereochemical integrity. Various esters can be synthesized using a broad range of alcohols and unactivated aldehydes.
B. E. Marki, K. A. Scheidt, Org. Lett., 2008, 10, 4331-4334.
N-Heterocyclic carbenes catalyze the oxidation of various allylic, propargylic, and benzylic alcohols to esters with manganese(IV) oxide in excellent yields. Saturated esters can also be accessed from aldehydes using this method. A desymmetration of meso-1,2-diols using a chiral catalyst is described.
B. E. Maki, A. Chan, E. M. Phillips, K. A. Scheidt, Org. Lett., 2007, 9, 371-374.
A copper(II)-catalyzed intermolecular three-component oxyarylation of allenes using arylboronic acids as a carbon source and TEMPO as an oxygen source proceeded under mild conditions with high regio- and stereoselectivity and functional group tolerance.
T. Itoh, Y. Shimizu, M. Kanai, Org. Lett., 2014, 16, 2736-2739.
A direct conversion of activated primary alcohols into terminal alkynes through a sequential one-pot, two-step process involving oxidation with manganese dioxide and then treatment with the Bestmann-Ohira reagent proceeds efficiently under mild reaction conditions with a range of benzylic, heterocyclic and propargylic alcohols.
E. Quesada, R. J. K. Taylor, Tetrahedron Lett., 2005, 46, 6473-6476.
Permanganate supported on active manganese dioxide can be used effectively for the oxidation of arenes, alcohols and sulfides under heterogeneous or solvent-free conditions.
A. Shaabania, P. Mirzaeia, S. Naderia, D. G. Leeb, Tetrahedron, 2004, 60, 11415-11420.
A method for the synthesis of N-aroylated sulfoximines involves a manganese oxide promoted C-H activation of methyl arenes to form an aroyl intermediate which then reacts readily with N-chlorosulfoximines to form a series of valuable aroyl sulfoximine derivatives in high yields.
D. L. Priebbenow, C. Bolm, Org. Lett., 2014, 16, 1650-1652.
A copper-catalyzed intermolecular carboamination of potassium N-carbamoyl-β-aminoethyltrifluoroborates with terminal, 1,2-disubstituted, and 1,1-disubstituted vinylarenes bearing a number of functional groups provides 2-arylpyrrolidines. 1,3-Dienes are also good substrates, and their reactions give 2-vinylpyrrolidines.
C. Um, S. R. Chemler, Org. Lett., 2016, 18, 2515-2518.
The reaction of 1-aryl-2,2,2-trifluorodiazoethanes with alkenes provides trifluoromethyl-substituted cyclopropanes with high diastereoselectivity and enantioselectivity in the presence of an adamantylglycine-derived dirhodium complex Rh2(R-PTAD)4 as catalyst.
J. R. Denton, D. Sukumaran, H. M. L. Davies, Org. Lett., 2007, 9, 2625-2628.
A step-economical access to polysubstituted aminoimidazoles via alkene vicinal C-N bonds formation of 2-bromo-2-alkenones with guanidine avoids a NH-protection/derivatization strategy. The reaction involves a tandem pathway of aza-Michael addition, SN2, and a unique redox-neutral process and offers an excellent substrate scope.
S. K. Guchhait, N. Hura, A. P. Shah, J. Org. Chem., 2017, 82, 2745-2752.
4-Substituted-1,4-dihydropyridines are readily and efficiently aromatized in only one minute using commercial manganese dioxide in the absence of an inorganic support at 100 °C under microwave irradiation. This rapid procedure gives the dehydrogenated or 4-dealkylated product in excellent yield.
M. C. Bagley, M. C. Lubinu, Synthesis, 2006, 1283-1288.