An operationally simple and very efficient Reformatsky reaction of aldehydes has been carried out in THF in the presence of low valent iron or copper which were prepared in situ employing a bimetal redox strategy through reduction of Fe(III) or Cu(II) salts with magnesium.
A. Chattopadhyay, A. Kr. Dubey, J. Org. Chem., 2007, 72, 9357-9359.
A user-friendly and operationally simple Ni-catalyzed carboxylation of unactivated primary alkyl bromides and sulfonates with CO2 at atmospheric pressure is characterized by its mild conditions and remarkably wide scope without the need for air- or moisture-sensitive reagents.
Y. Liu, J. Cornella, R. Martin, J. Am. Chem. Soc., 2014, 136, 11212-11215.
An efficient Ni-catalyzed reductive carboxylation of brached and linear allylic alcohols with CO2 provides linear β,γ-unsaturated carboxylic acids as the sole regioisomer with generally high E/Z stereoselectivity. In addition, the carboxylic acids can be generated from propargylic alcohols via a hydrogenation step made possible by a Ni hydride intermediate produced by a hydrogen atom transfer from water.
Y.-G. Chen, B. Shuai, C. Ma, X.-J. Zhang, P. Fang, T.-S. Mei, Org. Lett., 2017, 19, 2969-2972.
A Ni-catalyzed regiodivergent reductive carboxylation of allyl esters with CO2 is mild, user-friendly, and operationally simple. The reaction is characterized by an exquisite selectivity profile that is dictated by the ligand backbone.
T. Moragas, J. Cornella, R. Martin, J. Am. Chem. Soc., 2014, 136, 17702-17705.
An intermolecular pinacol coupling of aromatic or aliphatic carbonyl compounds catalyzed by a complex of samarium diiodide (SmI2) with tetraglyme in the presence of Me2SiCl2 and Mg is described. High diastereoselectivity has been achieved in reactions with aliphatic and aromatic aldehydes. De values of up to 99% have been achieved in intramolecular pinacol coupling reactions.
H. C. Aspinall, N. Greeves, C. Valla, Org. Lett., 2005, 7, 1919-1922.
Rieke Ni generated in situ was able to promote the pinacol coupling of various carbonyls efficiently. Another catalytically effective, cheaper and more convenient NiCl2(Cat.)/Mg/TMSCl system was designed and developed further successfully. Single-electron transfer (SET) mechanisms for the coupling reactions and the DL/meso diastereoselectivity were also explained.
L. Shi, C.-A. Fan, Y.-Q. Tu, M. Wang, F.-M. Zhang, Tetrahedron, 2004, 60, 2851-2855.
Magnesium in methanol is an effective reagent for the chemoselective reduction of ozonides and other peroxides. Mg/MeOH is significantly more reactive than Me2S or PPh3 and somewhat more reactive than Zn/HOAc.
P. Dai, P. H. Dussault, T. K. Trullinger, J. Org. Chem., 2004, 69, 2851-2852.
Mercury(II) chloride efficiently activates magnesium metal to induce a desulfonylative trifluoromethylation process. The new reductive trifluoromethylation provides an alternative method for efficient trifluoromethylation of non-enolizable or enolizable aldehydes with readily available phenyl trifluoromethyl sulfone reagent.
Y. Zhao, J. Zhu, C. Ni, J. Hu, Synthesis, 2010, 1899-1904
An operationally simple cross-coupling reaction between aryl halides and alkyl halides with high selectivity utilizes CoCl2/Me4-DACH as a catalyst system. The underlying domino process exhibits high sustainability as it obviates the need for the pre-formation and handling of stoichiometric amounts of hazardous Grignard compounds.
W. M. Czaplik, M. Mayer, A. J. von Wangelin, Synlett, 2009, 2931-2934.
A magnesium-mediated reductive cross-coupling between benzyl chlorides and aryl chlorides or fluorides gives diarylmethanes in good to excellent yields in a one-pot manner using easy-to-access mixed PPh3/NHC Ni(II) complexes of Ni(PPh3)(NHC)Br2 as catalyst precursors.
J. Zhang, G. Lu, J. Xu, H. Sun, Q. Shen, Org. Lett., 2016, 18, 2860-2863.
A low-valent titanium generated in situ from Ti(O-i-Pr)4, Me3SiCl, and Mg powder in THF reacted with a broad range of sulfonamides in a reductive bond cleaving pathway to provide the corresponding amines, hydrocarbons and thiols. The reagent could also cleave sulfonates to the corresponding alcohols.
N. Shohji, T. Kawaji, S. Okamoto, Org. Lett., 2011, 13, 2626-2629.