Base‐Catalyzed Hydration of Silicon‐Containing Activated Alkynes: The Effect of Substituents at the Triple Bond

Abstract

Metal‐catalyzed hydration of alkynes is rapidly developing research direction in organic synthesis. However, base‐catalyzed hydration of activated acetylenes remains much less studied. In contrast to the metal‐catalyzed reactions leading to carbonyl compounds, base‐catalyzed hydration gives vinyl ethers of different structure or cyclic products depending on the nature of substituents. So, it is found that 1,4‐diazabicyclo [2.2.2]octane (DABCO)‐catalyzed hydration of trimethylsilylated electron‐deficient alkynes of general formula Me3SiC≡CCOX (X=Ph, NR1R2, OEt) proceeds at room temperature to afford push‐pull divinyl ethers in 56–94 % yields, while 4‐trimethylsilyl‐3‐butyne‐2‐one (X=Me) reacts non‐selectively delivering both symmetrical and unsymmetrical divinyl ethers (dimerization products). Contrary to ketones, amides and esters, 3‐trimethylsilylpropynal gives under the same conditions 4H‐pyran, as we shown earlier.

Hydrogen Bonding-directed Sequential 1,6/1,4-Addition of Heteroatom Nucleophiles onto Electron-deficient 1,3-Diynes

“…Aryl ketones 1b–f provided higher yields of amine-addition products 2ba–fa (68–81%) than those of alkyl ketone-derived products 2ha–ja (23–34%) with 2ka (76%) as an exception. This is most likely because of enolization when amines are used as a nucleophile, which is evidenced by isolation of 2ia′ , 17 which could be converted to 2ia upon heating. 18 Reactions of aryl ketones with tert -propargylic carbon ( 1c and 1d ) also provided higher yields of methanol addition products 2cb and 2db (85% and 77%) than those of alkyl ketones 1h–k (48–70%) indicating that electron withdrawing aryl groups make the substrate more electrophilic for conjugate addition than electron donating alkyl groups.…”

A New Family of Vinyl Selenocyanates with the Amide Function Based on the Reaction of Potassium Selenocyanate with 3-Trimethylsilyl-2-Propynamides

“…In the course of the study, the influence of the nature of the N-substituent of the amide group of the starting acetylenic amides 1a-l on their reactivity in the nucleophilic addition of selenocyanate at the triple bond was found. Obviously, the different reactivity in the series of acetylenic amides 1a-l depends on the magnitude of the electron-withdrawing effect of the amide group, which polarizes the triple bond to a different degree, depending on the donor-acceptor properties of the N-substituent [70].…”

Regio- and Stereoselective Synthesis of (Z,Z)-Bis(3-amino-3-oxo-1-propenyl) Selenides and Diselenides Based on 2-propynamides: A Novel Family of Diselenides with High Glutathione Peroxidase-like Activity

“…2-Propynamides 1a-i with the terminal triple bond were obtained in high yields by desilylation of 3-(trimethylsilyl)-2-propynamides under the action of potassium carbonate in methanol at room temperature (Scheme 1). An efficient and convenient method for the preparation of 3-(trimethylsilyl)-2-propynamides based on propargyl alcohol was previously developed at this institute [52][53][54] and opened up the possibility of using these reagents in organic synthesis [55][56][57][58].…”

“…namides based on propargyl alcohol was previously developed at this institute [52][53][54] and opened up the possibility of using these reagents in organic synthesis [55][56][57][58].…”