LAH, Lithium aluminum hydride, Lithium tetrahydridoaluminate
LiAlH4 is a very common, strong reducing agent, which reduces a vast number of different functional groups.
The preparation of alkenyl halides of any length from inexpensive starting reagents is reported. Standard organic transformations were used to prepare straight-chain α-olefin halides in excellent overall yields with no detectable olefin isomerization and full recovery of any unreacted starting material.
T. W. Baughman, J. C. Sworen, K. B. Wagener, Tetrahedron, 2004, 60, 10943-10948.
A tethered alkene functionality can be used as a traceless directing group for a zirconium catalyzed reductive cleavage of Csp3 and Csp2 carbon-heteroatom bonds, including C-O, C-N, and C-S bonds. The reaction is especially useful for cleavage of homoallylic ethers and the removal of terminal allyl and propargyl groups.
C. Matt, F. Kölblin, J. Streuff, Org. Lett., 2019, 21, 6909-6913.
Secondary α-chloroketimines react with lithium aluminium hydride in ether to afford mixtures of cis- and trans-1,2,3-trisubstituted aziridines by nucleophilic addition of hydride across the imino bond and subsequent intramolecular nucleophilic substitution. Tertiary α-chloroketimines react similarly to yield 1,2,2,3-tetrasubstituted aziridines. α,α-Dichloroketimines react in a stereospecific way to afford cis-aziridines, exclusively.
N. De Kimpe, L. Moens, Tetrahedron, 1990, 46, 2965-2974.
Various phosphine oxides are efficiently reduced by the use of a methylation reagent, followed by lithium aluminum hydride. Optically active P-chirogenic phosphine oxides are reduced with inversion of configuration.
T. Imamoto, S.-i. Kikuchi, T. Miura, Y. Wada, Org. Lett., 2001, 3, 87-90.
Phenol carbamates undergo an anionic ortho-Fries rearrangement to their corresponding amides in the presence of LDA. Sterically hindered substrates can be converted with s-BuLi/TMEDA at -90°C. The amides can be efficiently reduced with lithium aluminum hydride to the corresponding Mannich bases.
N. Assimomytis, Y. Sariyannis, G. Stavropoulos, P. G. Tsoungas, G. Varvounis, P. Cordopatis, Synlett, 2009, 2777-2782.
Trifluoromethyl arenes were reduced with lithium aluminum hydride to give toluene derivatives in good yields in the presence of 5 mol % of niobium(V) chloride. Stepwise, partial reduction of a bis(trifluoromethyl) arene was also demonstrated.
K. Fuchibe, Y. Ohshima, K. Mitomi, T. Akiyama, Org. Lett., 2007, 9, 1497-1499.
Treatment of substituted arylbromides with tert-butyllithium in diethyl ether at -78˚C, followed by the addition to dichlorodiethoxysilane, leads to the quantitative formation of diaryldiethoxysilanes. Diaryldiethoxysilanes can be reduced to the corresponding diarylsilanes by stirring with lithium aluminum hydride in diethyl ether. This method avoids the handling of gaseous and explosive dichlorosilane.
P. Gigier, W. A. Herrmann, F. E. Kühn, Synthesis, 2010, 1431-1432.
A stereoselectiv hydrodefluorination reaction of trifluoromethylated alkenes with LiAlH4 provides terminal monofluoroalkenes in very good yields and diastereoselectivities. Mechanistic studies suggested a hydroalumination reaction followed by a stereoselective fluoride elimination.
P. Poutrel, X. Pannecoucke, P. Jubault, T. Poisson, Org. Lett., 2020, 22, 4858-4863.