Iridium-Catalyzed Reactions Involving Transfer Hydrogenation, Addition, N-Heterocyclization, and Alkylation Using Alcohols and Diols as Key Substrates

Abstract

This account gives an overview of iridium-catalyzed reactions developed by our group using mainly alcohols and diols as substrates. In the presented reactions, the iridium catalyst serves as a hydrogen acceptor from the alcohols giving iridium hydride, which is a key transient species. Herein, we report hydrogenation, alkylation, esterification, N-heterocyclization, and coupling reactions using alcohols and diols as reagents.

Amination and dehydration of 1,3-propanediol by hydrogen transfer: reactions of a bio-renewable platform chemical

“…N-alkylation of aniline using 1,3-PDO may be expected to generate mono or di-amines or quinolines (particularly at higher temperatures), [8][9][10][11][12][13] Unexpected, was the observation of the product of concurrent dehydration (5 in Scheme 1). 2 In the reaction of aniline with 1,3-propanediol catalyzed by 1 in toluene in a sealed tube at 115 1C, diamination and dehydration were observed, 1,3-PDO was converted to yield products 4 and 5 (65% and 35% respectively by 1 H NMR).…”

Organometallic hydrogen transfer and dehydrogenationcatalysts for the conversion of bio-renewable alcohols

“…Ishii and co-workers have recently reviewed their contribution to this field. 63 Indoles have been prepared by employing [Cp*IrCl 2 ] 2 (1 mol%) with an acid promoter, 53 methanesulfonic acid was particularly promoting (Scheme 23). Reaction times were longer (2 days) than those required for RuCl 3 /phosphine based systems.…”

Iridium‐Catalyzed Reactions of ω‐Arylalkanols to α,ω‐Diarylalkanes

“…With regard to the selection of an Ir catalyst, [(Cp*IrCl 2 ) 2 ] gave the highest catalytic performance, in both activity and selectivity ( [12][13][14] resulted in low yields of 2 a (< 6 %); 1,3-diphenyl-1-propene (3 a; 5-15 %) and toluene (4 a; < 9 %) were formed as by-products (Table 1, entries 2-5).…”

“…It is well known that Ir and Ru complexes serve as efficient catalysts for hydrogen transfer from alcohols to aldehydes [12] and this catalysis has been used in a alkylations of carbonyl and related compounds, [12,13] and b alkylations (Guerbet reaction) of alcohols. [12,14] Furthermore, Ir, Ru, and Rh complexes are known to show efficient catalytic activity in the decarbonylation of aldehydes.…”

“…It is well known that Ir and Ru complexes serve as efficient catalysts for hydrogen transfer from alcohols to aldehydes [12] and this catalysis has been used in a alkylations of carbonyl and related compounds, [12,13] and b alkylations (Guerbet reaction) of alcohols. [12,14] Furthermore, Ir, Ru, and Rh complexes are known to show efficient catalytic activity in the decarbonylation of aldehydes. [15] Herein, we report a novel general synthetic method for producing a,w-diarylalkanes 2 from w-arylalkanols 1 by dehydrogenation/b-alkylation (step 1) and a subsequent dehydrogenation/decarbonylation (step 2), either by a direct one-step method (Scheme 1, route A) or a sequential twostep method (Scheme 1, route B).…”