Catalytic Enantioselective Allylations of Acetylenic Aldehydes via 2-Propanol-Mediated Reductive Coupling

Abstract

Cyclometalated π-allyliridium C,O-benzoates modified by ( S)-SEGPHOS or ( S)-Cl,OMe-BIPHEP catalyze enantioselective 2-propanol-mediated reductive couplings of diverse nonmetallic allyl pronucleophiles with the acetylenic aldehyde TIPSC≡CCHO. Absolute stereochemistries of the resulting secondary homoallylic-propargylic alcohols were assigned using Rychnovsky's competing enantioselective conversion method.

Gallium(III) Corrole Complexes as Near‐Infrared Emitter – Synthesis, Computational and Photophysical Study

“…All chemicals were purchased from Alfa Aesar, Fluka, Merck, or Sigma‐Aldrich and were used without further purification. 5‐(4‐t‐butylphenyl)dipyrromethane 1 , 3‐triisopropylsilylpropynal 2 , 5‐triisopropyl‐ethynyldipyrromethane 3 , gallium(III) pyridine‐5,10,15‐trispentafluoro‐phenylcorrole (GaTpFPC) were synthesized according to literature procedures [54,53,23] . DCM stored over molar sieve MB‐SPS‐7 using an M. Braun Inert gas‐System GmbH (Garching, Germany) under argon atmosphere.…”

Stereoselective Carbocyclization of Vinyloxiranes Catalyzed by Lewis Acids: Construction of the Musellarin Tricyclic Core

“…Then, ring‐closing metathesis of the esters afforded the γ‐lactones with the requisite cis‐ and trans stereochemistry for the construction of musellarin A and E (Scheme 4). 11 …”

Enantioselective Iridium‐Catalyzed Allylation of Acetylenic Ketones via 2‐Propanol‐Mediated Reductive Coupling of Allyl Acetate: C14‐C23 of Pladienolide D

“…It was posited that acetylenic ketones might participate in efficient alcohol‐mediated carbonyl allylation due to electrophilic activation associated with the negative inductive effect of the alkyne . Although isolated examples have been reported, only one systematic study on the asymmetric allylation of acetylenic ketones appears in the literature, which exploits an allylzinc reagent bound by a stoichiometric chiral modifier .…”

“…Guided by our prior work on the transfer hydrogenative allylation of acetylenic aldehydes, methyl ketone 1 a (100 mol %, [Si]= i Pr 3 Si) was exposed to allyl acetate 2 a (200 mol %) and 2‐propanol (200 mol %) in the presence of Cs 2 CO 3 (50 mol %) and the commercially available π‐allyliridium‐ C , O ‐benzoate modified by ( S )‐SEGPHOS, ( S )‐Ir‐ I (5 mol %), in anhydrous THF (Table , entry 1). The desired product of ketone allylation was formed in 22 % yield in highly enantiomerically enriched form.…”