Methylcopper(I)-catalyzed selective conjugate reduction of .alpha.,.beta.-unsaturated carbonyl compounds by di-iso-butylaluminum hydride in the presence of hexamethylphosphoric triamide

Tandem Michael−Wittig−Horner Reaction: One-Pot Synthesis of δ-Substituted α,β-Unsaturated Carboxylic Acid Derivatives − Application to a Concise Synthesis of (Z)- and (E)-Ochtoden-1-al

“…As claimed, the yields were significantly increased (Entries 2 versus 1 and 4 versus 3). Furthermore, using a procedure first described by Tsuda et al, [10] we were also able firstly to reduce the CϭC double bond of the enone by conjugate addition of a hydride species before performing the Scheme 6 WittigϪHorner reaction. In this case, the overall yield appeared less significant than expected.…”

Indium(III) Acetate-Catalyzed 1,4-Reduction and Reductive Aldol Reactions of α-Enones with Phenylsilane

“…In the 1,4-reduction of 1a, the use of PhSiD 3 instead of PhSiH 3 provided 2a-d by b-deuteration, while the use of EtOD as solvent resulted in a-deuteration (Scheme 1). Judging from these results, the present 1,4-reduction could proceed via the following mechanism (Scheme 2): (1) transmetalation between In(OAc) 3 and PhSiH 3 in EtOH forms an indium hydride species (HInL 2 , L = OAc, OEt), (2) 1,4-addition of the hydride to an aenone 1 leads to the corresponding indium enolate 4, (3) solvolysis of 4 gives the 1,4-reduction product 2 and InL 3 , (4) transmetalation between InL 3 and PhSiH 3 regenerates HInL 2 .…”

“…The In(OAc) 3 catalyzed reaction in THF at 70°C gave the desired ketone 2a as the major product; however, a significant amount of dimerization product 3a was also obtained (entry 1). 10 The formation of 3a is attributable to the Michael addition of indium enolate intermediate 4a to 1a.…”

“…The use of EtOH as solvent further enhanced the reaction rate to enable the reduction at room temperature (entry 4). 11 Thus the In(OAc) 3 -catalyzed reduction of 1a in EtOH was completed in 1.5 hours at room temperature to give 2a in 90% yield. 12 Indium metal was deposited under these reaction conditions.…”

2.06 Formation of Enolates

“…[115][116][117] The role of copper and HMPA is crucial, for without these 1,2-reduction of the carbonyl group takes place. The effect of copper(I) on conjugate addition is not unexpected.…”