19 research outputs found
Stereoselective Synthesis of Pyrroloisoindolone and Pyridoisoindolone via aza-Prins Cyclization of Endocyclic <i>N</i>‑Acyliminium Ions
A simple
methodology has been developed for the synthesis of substituted
pyrroloisoindolone and pyridoisoindolone via aza-Prins cyclization
of endocyclic <i>N</i>-acyliminium ions, which are derived
from the triflic acid treatment of regioselectively reduced <i>N</i>-homopropargyl imides in excellent yields. The reaction
is highly diastereoselective, and only one diastereoisomer is formed
during the reaction. The methodology can be utilized for the synthesis
of pyrimidoisoindole
Diastereoselective Synthesis of Substituted Morpholines from <i>N</i>‑Tethered Alkenols: Total Synthesis of (±)-Chelonin A
Intramolecular
cyclization of nitrogen tethered alkenols catalyzed
by palladium chloride leads to substituted morpholines in good yields.
The methodology was used for the total synthesis of (±)-chelonin
A
Diastereoselective Synthesis of Substituted Tetrahydrofurans via Prins Cyclization of Enol Ethers
Indium triflate can be efficiently
used for Prins cyclization of
acrylyl enol ethers to give tetrahydrofuran ring stereo- and regioselectively
in good yields. The formation of five-membered rings is against the
Baldwin’s rule
Stereo- and Regioselective Synthesis of 4‑Vinylpyrrolidine from N‑Tethered Alkyne-Alkenol
IndiumÂ(III)
chloride can be efficiently used for the synthesis
of 4-vinylpyrrolidine from N-tethered alkyne-alkenol in good yields.
The reaction is highly stereo- and regioselective
Diastereoselective Synthesis of Substituted Tetrahydrothiopyrans via (3,5)-Thionium–Ene Cyclization Reaction
Tetrahydrothiopyrans have been efficiently synthesized
in good
yields with excellent diastereoselectivity from aldehydes and substituted
5-methylhex-4-ene-1-thiol via (3,5)-thionium–ene cyclization
reaction mediated by boron trifluoride etherate
Diastereoselective Synthesis of Substituted Tetrahydrothiophenes and -thiopyrans via Thia-Prins Cyclization Reaction
Tetrahydrothiophenes and -thiopyrans
have been efficiently synthesized
from thioacrylates via thia-Prins cyclization reaction mediated by
trimethylÂsilylÂtrifluoroÂmethaneÂsulfonate with
good diastereoselectivity and in good to high yields
Diastereoselective Synthesis of Substituted Tetrahydrothiopyrans via (3,5)-Thionium–Ene Cyclization Reaction
Tetrahydrothiopyrans have been efficiently synthesized
in good
yields with excellent diastereoselectivity from aldehydes and substituted
5-methylhex-4-ene-1-thiol via (3,5)-thionium–ene cyclization
reaction mediated by boron trifluoride etherate
Synthesis of Tetrahydro‑1<i>H</i>‑indeno[1,2‑<i>b</i>]pyridine via Cascade Cyclization and Friedel–Crafts Reaction
A convenient protocol
has been established for the synthesis of
1-tosyl-2,3,4,5-tetrahydro-1<i>H</i>-indenoÂ[1,2-<i>b</i>]Âpyridine via cascade cyclization and Friedel–Crafts
reaction of 4-methyl-<i>N</i>-(pent-4-yn-1-yl)Âbenzenesulfonamides
and aldehydes in good yields. The methodology has been used for the
total synthesis of the antidepressant agent (±)-5-phenyl-2,3,4,4a,5,9b-hexahydro-1<i>H</i>-indenoÂ[1,2-<i>b</i>]Âpyridine
Diastereoselective Synthesis of Dihydropyrans via Prins Cyclization of Enol Ethers: Total Asymmetric Synthesis of (+)-Civet Cat Compound
Trimethylsilyl
trifluoromethanesulfonate (TMSOTf) can be efficiently
used for Prins cyclization of acrylyl enol ethers to 5,6-dihydro-2<i>H</i>-pyran-2-acetates stereo- and regioselectively in good
yields. The methodology was used for the total synthesis of natural
product (+)-civet
Stereoselective Synthesis of Amido and Phenyl Azabicyclic Derivatives via a Tandem Aza Prins-Ritter/Friedel–Crafts Type Reaction of Endocyclic <i>N</i>‑Acyliminium Ions
A simple protocol is described for
the synthesis of amido and phenyl
hexahydroindolizin-3Â(2<i>H</i>)-one, hexahydro-1<i>H</i>-quinolizin-4Â(6<i>H</i>)-one, and 1,3,4,10<i>b</i>-tetrahydropyridoÂ[2,1<i>-a</i>]Âisoindol-6Â(2<i>H</i>)-one derivatives via endo-trig (aza-Prins type) cyclization
followed by an intermolecular Ritter/Friedel–Crafts reaction
of cyclic <i>N</i>-acyliminium ions, which are derived from
the boron trifluoride etherate treatment of regioselectively reduced <i>N</i>-homoallyl imides. The reactions are highly diastereoselective
with excellent yields