A Mild Method for the Preparation of γ‐Hydroxy‐α,β‐Acetylenic Esters

Abstract

The beauty of silver has been demonstrated in the alkynylation of functionalized aldehydes and ketones. Silver acetylides of alkynyl propiolates undergo addition to carbonyl compounds in the presence of [Cp2ZrCl2] and AgOTf (see scheme) in a reaction that is compatible with both base‐sensitive and acid‐sensitive functional groups. Tf=trifluoromethanesulfonyl.

Development of Zn–ProPhenol‐Catalyzed Asymmetric Alkyne Addition: Synthesis of Chiral Propargylic Alcohols

“…[26] Propiolate donors have traditionally been difficult substrates for asymmetric alkynylation due to their propensity to decompose in the presence of Lewis acids and nucleophiles. [27] Methyl propiolate ultimately proved to be one of the most effective alkynes under Zn-ProPhenol alkynylation conditions (Table 4). Excellent results were obtained with a range of α,β-unsaturated aldehydes, including ( E )-non-2-enal, which provided 97% ee with methyl propiolate (entry 2), a major improvement from the 36% ee obtained with TMS-acetylene.…”

Molecular and Crystal Structure of Chlorido[2-(N,N,N',N'- tetramethylamidinio)ethynido]silver

“…To our surprise, however, an X-ray crystal structure determination of the product obtained from 1-Cl and Ag 2 O revealed the presence of the simple σ -alkynyl silver complex 3 (molecular formula C 7 H 12 AgClN 2 ) (vide infra). NHC complexes of the type [(NHC) 2 Ag] + [AgHal 2 ] − have appeared in the literature, but their structure was not always proven rigorously [10,24]. Nolan and coworkers [25] (4)Å).…”

Organic Base‐Catalyzed Stereoselective Isomerizations of 4‐Hydroxy‐4‐phenyl‐but‐2‐ynoic Acid Methyl Ester to (E)‐ and (Z)‐4‐Oxo‐4‐phenyl‐but‐2‐enoic Acid Methyl Esters

“…[11] Although Wittigtype condensations [6] and other methods [12 -14] have been employed to form E-A, additional methods would involve g-hydroxy-a,b-alkynoic esters B as precursors. These esters are easy to prepare [15,16] even in the presence of reactive functional groups. [16] In principle, concomitant oxidation of the g-hydroxy group and reduction of alkyne of B should afford E-A or Z-A.…”

“…These esters are easy to prepare [15,16] even in the presence of reactive functional groups. [16] In principle, concomitant oxidation of the g-hydroxy group and reduction of alkyne of B should afford E-A or Z-A.…”