Remarkably Selective Reduction of the α,β-Carbon−Carbon Double Bond in Highly Activated α,β,γ,δ-Unsaturated Alkenes by the InCl₃−NaBH₄ Reagent System

Abstract

A combination of sodium borohydride and a catalytic amount of indium(III) chloride in acetonitrile reduces exclusively the alpha,beta-carbon-carbon double bond in alpha,beta,gamma,delta-unsaturated diaryl ketones, dicarboxylic ester, cyanoester, and dicyano compounds.

Sodium borohydride-nickel chloride hexahydrate in EtOH/PEG-400 as an efficient and recyclable catalytic system for the reduction of alkenes

“…Importantly, the appropriate amounts of the NaBH 4 were only 0.5 molar equivalents (entry 4), which were lower than those in the earlier reports. 12,15,23,24 This is possibly because the hydrogen source for the reduction can be sufficiently derived from the B-H of NaBH 4 and the O-H of ethanol in our catalytic system (ideally 1 molar of NaBH 4 can reduce 4 molar of alkenes with ethanol), as recently reported by Bai et al for the semihydrogenation of alkynes with NaBH 4 in methanol. 25 The activity of the in situ generated Ni (0) NPs catalyst in EtOH/PEG-400 (3/2 ratio) had also been compared with the commercial RANEY® nickel catalyst.…”

Remarkably Chemoselective Reduction of Unmodified Baylis-Hillman Adducts by InCl3/NaBH4: Application to the Stereoselective Synthesis of Trisubstituted Alkenones Including Two Alarm Pheromones

“…The use of this reagent was reported earlier to reduce the conjugated double bond of a,b,g,d-unsaturated carbonyl compounds. 21 The stereochemistry of the product 2c was found to be solely E as determined by comparing the 1 H NMR, 13 C NMR and IR data with that reported previously. 22 This was further confirmed by the aid of 1 H NOESY experiments.…”

“…In absence of InCl 3 the reaction did not proceed chemoselectively. It may be speculated that chloroindium hydride (Cl 2 InH) 21 formed by the combination of NaBH 4 and InCl 3 might be the active species responsible for the reduction. AlCl 3 / NaBH 4 system underwent vigorous reaction with the adduct 1c to furnish a complex mixture of products and thus this reducing system was not useful for the present conversion.…”

Selective 1,4‐Reduction of Chalcones with Zn/NH4Cl/C2H5OH/H2O

“…It has always been a challenging problem in organic synthesis. 5 Numerous methodologies have been reported in the literature, for example, Pd, Rh, Pt, Ni, Ir, Co and their complexes, [6][7][8][9] hydrides of Sn, Se, Te, B; 10,11 sodium dithionite 12,13 and sodium borohydride [14][15][16] have also been reported to be useful for the hydrogenation of a,b-unsaturated carbonyl compounds. However, some of these systems suffer from their own limitations: handling of reagents, strict reaction conditions, temperature maintenance, long reaction time, cost and poor yields of the desired product.…”