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 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.
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.
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.