New and effective reagents for 1,4 reduction of .alpha.,.beta.-unsaturated ketones, LiAlH4-CuI and Its reactive species H2AlI

Reductions of conjugated carbonyl compounds with copper hydride - preparative and mechanistic aspects

“…A simple mixture of lithium aluminum hydride and cuprous iodide in the ratio of 1:4 is successful in conjugate reduction of acyclic «,/3-unsaturated ketones, but fails for 2-cyclohexenone derivatives, and no results were reported with unsaturated esters. 19 An intriguing feature of this work is that the results can be interpreted as reactions of H2A1I or HA1I2; no copper hydride need be invoked. 19 From the experiments of House and DuBose,20 and consistent with the stoichiometry generally used to prepare the active reagents, CuH itself does not add to conjugated ketones, but the "ate" complexes such as 2-4 are generally successful.…”

“…19 An intriguing feature of this work is that the results can be interpreted as reactions of H2A1I or HA1I2; no copper hydride need be invoked. 19 From the experiments of House and DuBose,20 and consistent with the stoichiometry generally used to prepare the active reagents, CuH itself does not add to conjugated ketones, but the "ate" complexes such as 2-4 are generally successful.…”

Synthesis of Indole‐Derived Allocolchicine Congeners through Pd‐Catalyzed Intramolecular C‐H Arylation Reaction

“…The use of other reagents known to perform well in the hydrogenation reactions of chalcone‐type substrates [e.g. LiAlH 4 /CuI,35 catecholborane,36 or H 2 /Pd(C)/Ph 2 S37] only led to mixtures of over‐reduction products in this case. Only high‐pressure hydrogenation of 31 in the presence of Adams's catalyst (50 atm H 2 , 10 mol‐% PtO 2 , EtOAc, 5 d) also afforded 32 in a reasonable yield of 75 %.…”

Synthesis of (±)-Tetrabenazine by Visible Light Photoredox Catalysis

“…Selective reduction of the alkene in 14 was not trivial–several conditions for 1,4-hydride delivery instead predominantly gave the undesired 1,2-reduction product. 68–71 Hydrogenation under acidic conditions ultimately proved to be rapid and high yielding process, giving 6b in 79% yield. Addition of TFA was essential in this reaction, as hydrogenolysis of the benzylic amine and other side products were formed in its absence.…”