Organocatalytic Isomerization/Allylic Alkylation of <i>O</i>-Acylated Hemithioacetals and Their Application in Tandem Sequence to Access 2,7-Dioxabicyclo[2.2.1]heptan-3-one Derivatives
作者:Huan-Qing Zhang、Ji-Ming Xi、Wei-Wei Liao
DOI:10.1021/acs.joc.9b03172
日期:2020.1.17
preparation of α-hydroxy allylic thioesters via a Lewis base-catalyzed tandem isomerization/allylic alkylationprocess is reported. The resulting allylic thioesters can serve as valuable scaffolds to undergo a stereoselective intramolecular cyclization to deliver 2,7-dioxabicyclo[2.2.1]heptan-3-one derivatives in a catalytically atom-economic fashion.
Novel arylsulfonyl-dihydropyridine derivatives which are useful as calcium entry-blocker cardiovascular agents have the formula: ##STR1## or a pharmaceutically acceptable salt thereof, wherein R.sup.1 is hydrogen, lower alkyl, or lower alkoxyalkyl; R.sup.2 is hydrogen or chloro; and R.sup.3 is hydrogen, lower alkyl, or lower alkoxyethyl. A novel process using chiral sulfoxide reagents efficiently produces single isomers of these and other sulfonyl dihydropyridines.
A facile and efficient protocol for the α-benzoyloxylation of β-keto sulfides is presented. This methodology provides a step-economical, mild and practical access to highly functionalized α-O-benzoyloxy substituted β-keto sulfides, including those with quaternary carbons, which are not easily obtained through currently available methods.