Iron-Catalyzed β-Alkylation of Alcohols

Abstract

β-Branched alkylated alcohols have been prepared in good yields using a double-hydrogen autotransfer strategy in the presence of our diaminocyclopentadienone iron tricarbonyl complex Fe1. The alkylation of some 2-arylethanol derivatives was successfully addressed with benzylic alcohols and methanol as alkylating reagents under mild conditions. Deuterium labeling experiments suggested that both alcohols (2-arylethanol and either methanol or benzyl alcohol) served as hydrogen donors in this cascade process.

Carbon monoxide and hydrogen (syngas) as a C1-building block for selective catalytic methylation

“…Most recently, catalytic methods using methanol (CH 3 OH) for bmethylation of alcohols have been reported by us [21][22][23] and others. [24][25][26][27][28][29] These reactions occur via an integrated "borrowing hydrogen" reaction sequence involving metal-catalyzed re-Scheme 1 (a) Established processes for the conversion of syngas (CO/ H 2 ) to fuels and chemicals. (b) Novel catalytic reaction to use syngas as a methyl source for the b-methylation of alcohols.…”

(Cyclopentadienone)iron Complexes: Synthesis, Mechanism and Applications in Organic Synthesis

“…Next, Renaud and co‐workers further explored the catalytic activity of pre‐catalyst 11 a in tandem hydrogen borrowing processes. This pre‐catalyst was employed in β ‐alkylation of alcohols to afford the β ‐branched alcohols in good yields (Scheme 30A) [128] . Moreover, they reported the first iron‐catalyzed tandem three‐component alkylation of methyl ketones using benzyl alcohol and methanol, which gives access to the α ‐branched methylated ketones in moderate to high yields (Scheme 30B) [129] .…”

Recent Catalytic Applications of (Cyclopentadienone)iron Complexes

“…Very recently, Renaud and co‐workers further unfolded the potential of pre‐catalyst 1f , which was employed in tandem HB processes involving four HT steps: on the one hand, a tandem three‐component alkylation of methyl ketones was described, providing access to α‐methylated substituted ketones in one pot (Scheme A) . On the other hand, the β‐alkylation of alcohols with methanol and benzylic alcohols was reported (Scheme B) . Almost simultaneously, a paper by Morrill and co‐workers on the β‐methylation of alcohols with methanol using pre‐catalyst 1f was also published (Scheme C) …”

“…Three‐component HB alkylation of methyl ketones (A); β‐alkylation of alcohols reported by Renaud (B) and by Morrill (C) …”