Aldehydes and ketones influence reactivity and selectivity in nickel-catalysed Suzuki–Miyaura reactions

Abstract

Aldehydes and ketones can have beneficial or detrimental effects on nickel-catalysed reactions. When present on the aryl halide, excellent site-selectivity can be achieved; when present as additives, they inhibit the reaction.

Nickel‐Catalyzed Mono‐Selective α‐Arylation of Acetone with Aryl Chlorides and Phenol Derivatives

“…As expected, the less active unsubstituted chlorobenzene required heating at 80 °C to obtain similar yields. Of note, the same results were observed when the reaction of complex I with chlorobenzene was carried out in the presence of high excess of acetone, showing that acetone does not inhibit the oxidative addition process . Moreover, addition of chlorobenzene to a 1:1 mixture of I and ( L1 ) 2 Ni(0) led to quantitative formation of the oxidative addition product II b (Figure S7), indicating that ( L1 ) 2 Ni(0) is a reactive species …”

Reactions of nickel(0) with organochlorides, organobromides, and organoiodides: mechanisms and structure/reactivity relationships

“…Following on from this study, Cooper et al have investigated how common functional groups can interact with nickel(0) complexes and influence the rate and selectivity of oxidative addition (Scheme 6); 38 model nickel complexes with dppf ligands were utilised, and were compared to the analogous palladium complexes in Suzuki-Miyaura cross-coupling reactions. 39 Aldehyde-and ketonesubstituted aryl chlorides underwent unexpectedly rapid oxidative addition to [Ni(COD)(dppf)].…”

“…This exceptional reactivity of aromatic halides bearing aldehyde and ketone groups was then exploited to achieve selective Suzuki-Miyaura cross-coupling reactions; 38 Catalysis Science & Technology Mini review coupling was achieved at the site that was in conjugation with the aldehyde or ketone. This selectivity was such that the normal order of reactivity of aryl halides (I > Br > Cl) could be overturned, and was attributed to a 'ring-walking' process where the nickel moves from the initial site of coordination across a π-system to the aryl halide.…”

“…However, aldehydes and ketones (without halide functional groups) can act as inhibitors in these reactions, which prevents a potential drawback to the use of nickel catalysis. 38 Palladium has been shown not to interact strongly enough to induce these selectivity and inhibition effects observed with nickel. 39 In light of the much wider scope of electrophiles that are reactive with nickel in cross-coupling catalysis, 15,52 there can be selectivity challenge in nickel catalysis if the substrate is highly functionalised.…”

Direct Synthesis of Chain‐end‐functionalized Poly(3‐hexylthiophene) without Protecting Groups Using a Zincate Complex

“…The partial introduction of the COOH group at the terminal of P3HT was also confirmed by MALDI‐TOF mass spectroscopy (Figure S9, Supporting Information). The incomplete chain‐end functionalization reactions might be possibly caused by the presence of carbonyl groups from the large excess amount of terminator 1c′ , which may stabilize the ─C─Ni─Br terminal too much via a Ni/C═O interaction, [ 54 ] reducing the reactivity of the quasi‐living end of P3HT. Although increasing the ratio of [ t Bu 4 ZnLi 2 ] 0 /[ 1c ] 0 from 1.1 to 2.0 led to the complete Zn─I exchange reaction (100%), the chain‐end functionalization failed only reaching Fn = 23%, unfortunately ( 5f , Table 1, Figures S10 and S11, Supporting Information).…”