Catalytic properties of the Pd/C – triethylamine system

Abstract

In the presence of Pd/C and a catalytic amount of triethylamine, allylic alcohols are isomerized into the corresponding carbonyl compounds. The isomerization is accompanied by Pd/Ccatalyzed redox processes to give the saturated alcohol and the corresponding α,β-unsaturated ketone. Pd/C also catalyses the conjugate reduction of activated double bonds, using triethylamine as the source of the two newly incorporated hydrogen atoms, probably via a hydrido complex. During the reaction, the triethylamine undergoes unexpected Pd/C-catalyzed oligomerization to produce elongated aliphatic tertiary amines and ethylamine, which, in the conjugate reduction of α,β-unsaturated esters, resulted in the formation of the reduced ethylamides following a domino transamidation.

Asymmetric Total Synthesis of Propindilactone G

“…However, attempts with various Pd catalysts could not regio­selectively remove this double bond. On the other hand, treatment of 17 with Pd­(OH) 2 /C in the presence of Et 3 N under a balloon pressure of H 2 initiated a reductive isomerization to afford dienone 18 in 98% yield. Further treatment of 18 with m -CPBA in CH 2 Cl 2 afforded epoxide 19 in 73% yield as a single isomer.…”

Testing enabling techniques for olefin metathesis reactions of lipophilic substrates in water as a diluent

“…A well-known alternative strategy to perform metathesis reactions of demanding substrates is the use of microwave irradiation (Bantreil et al, 2012;Coquerel and Rodriguez, 2008; Ullah and Arshad, 2017), especially in (Samojłowicz et al, 2011b). In many cases, the use of this thermal activation technique has a general beneficial effect in terms of shorter reaction times, slower catalyst degradation, and less by-products formation (Kappe, 2019;Kappe et al, 2013).…”

Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine

“…[26,28,[50][51][52] Of particular note, Pd/C and Et 3 N have been used for reducing α,β-unsaturated carbonyls and a nitrile (at 120-200 °C) but, under the conditions, a vinyl chloride was not reduced at 140 °C. [53] A possible mechanism (Scheme 4B) involves oxidative-addition complex I reacting with an amineboron complex II, resulting in III. From III, one possibility is the direct formation of ArÀ PdÀ H (V) by transfer of "H" from the BÀ OH bond to the Pd center, with expulsion of metaborate (O=BÀ OH).…”