Asymmetric Direct Alkynylation Catalyzed by Chiral Ru−Bis(oxazolinyl)phenyl Complexes

Abstract

Propargylic alcohols were obtained with excellent enantioselectivities in the asymmetric direct alkynylation of aldehydes using 5 mol % of chiral ruthenium complexes containing the chiral bis(oxazolinyl)phenyl ligand.

Tandem semi-hydrogenation/isomerization of propargyl alcohols to saturated carbonyl analogues by dodecanethiolate-capped palladium nanoparticle catalysts

“…The ease of preparation of propargyl alcohols 1,2 and the broad utility of their reaction products have resulted in a vast library of effective reactions involving these compounds. 3–5 For example, propargyl alcohols can undergo full hydrogenation to saturated alcohols in the presence of an activated metal such as Pt or Pd in a pressurized, hydrogen rich environment.…”

Asymmetric Three-Component Coupling Reaction of Alkyne, Enone, and Aldehyde Catalyzed by Chiral Phebox Ruthenium Catalysts

“…The phebox-Ru complexes 1a−b were prepared by the reported method. 23,31 General Procedure of 5. A mixture of 1a (12 mg, 0.020 mmol), 2 (4.0 mmol), 3 (3.0 mmol), 4 (1.0 mmol), NaOAc (8 mg, 0.1 mmol), and ethanol (8 mg, 0.20 mmol) was stirred at 60°C for 24 h. After removal of volatile materials under reduced pressure, the residue was purified by column chromatography on silica gel with hexane/ethyl acetate to give 5 and 6 as a diastereomeric mixture.…”

“…23,24 These reactions are atom-economic transformations for the construction of alkyne derivatives. In the case of conjugate addition, a Ru enolate species could be formed by insertion of a terminal alkyne into an α,β-unsaturated carbonyl compound.…”

Catalytic Asymmetric Synthesis of Allylic Alcohols and Derivatives and their Applications in Organic Synthesis

“…A broad range of catalyst systems for the enantioselective alkynylation of carbonyl compounds have been developed (Scheme 124), [272] mostly involving the addition of alkynylzinc reagents, formed in situ in the presence of chiral promoters [273,274] 265-268, [273l-p] Figure 14), and catalytic [273a,d] or stoichiometric amounts [273b,c,e-u] of zinc reagents. Other metals such as copper [275] (with 269), indium [276] (74 b), ruthenium [277] (270), lithium [278] (271), and titanium [279] (74 a) have also been used. Catalytic asymmetric additions of trimethoxysilylalkynes to ketones [280] and of iodoalkynes to aldehydes [281] catalyzed by lithium binaphtholate 272 and chiral chromium complex 182 (NHK-type reaction), respectively, have also been studied ( Figure 14).…”