An efficient approach has been described for the synthesis of 3,5-disubstituted isoxazoles from propargylic alcohols. The strategy involves a one-pot p-TSA-catalyzed N-propargylation of protected hydroxylamines followed by a TBAF-mediated detosylative 5-endo-dig cyclization. The method was successfully used for the synthesis of various 3,5-disubstituted isoxazoles.
Cascade Reaction of Propargyl Amines with AgSCF<sub>3</sub>, as Well as One-Pot Reaction of Propargyl Amines, AgSCF<sub>3</sub>, and Di-<i>tert</i>-butyl Peroxide: Access to Allenyl Thiocyanates and Allenyl Trifluoromethylthioethers
An efficient cascade reaction of propargyl amines with AgSCF3 and KBr is developed, affording allenyl thiocyanates at room temperature in high yields. This transformation proceeds via the in situ formation of isothiocyanate intermediates, followed by a [3,3]-sigmatropic rearrangement. The resulting allenyl thiocyanates bearing 3-(electro-donating phenyl) substitutions without isolation can then be
Organoborane-catalyzed selective 1,2-reduction of alkynones with hydride transfer: Synthesis of benzyl alkynes
作者:Lele Zhai、Zhigang Yang、Qinghong Man、Mingyu Yang、Yangqing Ren、Lei Wang、Huilin Li、Xuegong She
DOI:10.1016/j.tetlet.2022.153645
日期:2022.2
Benzyl alkynes are important organic building blocks in organic synthesis. We report herein a B(C6F5)3-catalyzed site-selective 1,2-reduction of readily available alkynones to access benzyl alkynederivatives. Under the developed conditions, an array of alkynone substrates are transformed into the corresponding benzyl alkyne products in good to excellent yields. This transformation displays many advantages
Stereoselective Synthesis of (2<i>Z</i>,4<i>E</i>)-2,4-Pentadien-1-ols via Sequential 1,4-Elimination Reaction and [1,2]-Wittig Rearrangement Starting from (<i>E</i>)-4-Alkoxy-2-butenyl Benzoates
The sequential 1,4-elimination reaction of (E)-4-alkoxy-2-butenyl benzoates and [1,2]-Wittig rearrangement gave (2Z,4E)-2,4-pentadien-1-ols stereoselectively. Z-Selective formation of intermediary vinyl ethers, whose stereochemistry was well elucidated by the "syn-effect", was achieved by treatment of the 2-butenyl benzoates with KOH in the presence of Pd catalyst. The subsequent [1,2]-Wittg rearrangement by use of n-BuLi proceeded with retention of the stereochemistry of the intermediary vinyl ethers.