19 research outputs found
Synthesis of π‑Extended Fluoranthenes via a KHMDS-Promoted Anionic-Radical Reaction Cascade
An unprecedented
KHMDS-promoted domino reaction to furnish hydroxyfluoranthenes
is described. Biaryl compounds bearing acyl and naphthylalkenyl moieties
are transformed into 9-hydroxydibenzoÂ[<i>j</i>,<i>l</i>]Âfluoranthenes in a single step through the formation of an aromatic
and a pentagonal ring system. A variety of fluoranthenes including
those with extended π-conjugation, a heteroaromatic ring, and
unsymmetrical substituents could be synthesized. Mechanistic studies
reveal a unique reaction cascade where KHMDS acts as both a base and
a single-electron donor
An Arylative Ring Expansion Cascade of Fused Cyclobutenes via Short-Lived Intermediates with Planar Chirality
An arylative ring
expansion cascade has been developed for the
synthesis of medium-sized carbocycles from fused cyclobutenes. This
reaction proceeds through a short-lived <i>cis</i>,<i>trans</i>-cycloalkadiene intermediate that is formed by thermal
4Ď€ electrocyclic ring opening. Chirality transfer experiments
provide direct evidence for the transient generation of the intermediate
An Arylative Ring Expansion Cascade of Fused Cyclobutenes via Short-Lived Intermediates with Planar Chirality
An arylative ring
expansion cascade has been developed for the
synthesis of medium-sized carbocycles from fused cyclobutenes. This
reaction proceeds through a short-lived <i>cis</i>,<i>trans</i>-cycloalkadiene intermediate that is formed by thermal
4Ď€ electrocyclic ring opening. Chirality transfer experiments
provide direct evidence for the transient generation of the intermediate
Synthesis of Functionalized Polycyclic Aromatic Compounds via a Formal [2 + 2]-Cycloaddition
A base-promoted formal
[2 + 2]-cycloaddition of 2-acyl-2′-vinyl-1,1′-biaryls
was developed to provide polycyclic cyclobutanols as a step toward
the synthesis of substituted polycyclic aromatic hydrocarbons and
their heterocyclic analogues
Synthesis and Properties of Tribenzocarbazoles via an Acid-Promoted Retro (2+2)-Cycloaddition of Azapropellanes
We describe herein the development
of a new method to synthesize
tribenzocarbazoles via an acid-promoted retro (2+2)-cycloaddition
of azapropellanes, which were prepared by potassium hexamethyldisilazide
(KHMDS)-promoted (2+2)-cycloaddition. The tribenzocarbazoles showed
strong fluorescence both in solution and the solid state. The structural,
electronic, and optical properties of the synthetic tribenzocarbazoles
are also described
Synthesis and Properties of Tribenzocarbazoles via an Acid-Promoted Retro (2+2)-Cycloaddition of Azapropellanes
We describe herein the development
of a new method to synthesize
tribenzocarbazoles via an acid-promoted retro (2+2)-cycloaddition
of azapropellanes, which were prepared by potassium hexamethyldisilazide
(KHMDS)-promoted (2+2)-cycloaddition. The tribenzocarbazoles showed
strong fluorescence both in solution and the solid state. The structural,
electronic, and optical properties of the synthetic tribenzocarbazoles
are also described
Synthesis and Properties of Tribenzocarbazoles via an Acid-Promoted Retro (2+2)-Cycloaddition of Azapropellanes
We describe herein the development
of a new method to synthesize
tribenzocarbazoles via an acid-promoted retro (2+2)-cycloaddition
of azapropellanes, which were prepared by potassium hexamethyldisilazide
(KHMDS)-promoted (2+2)-cycloaddition. The tribenzocarbazoles showed
strong fluorescence both in solution and the solid state. The structural,
electronic, and optical properties of the synthetic tribenzocarbazoles
are also described
Development of a Brønsted Acid-Promoted Arene–Ynamide Cyclization toward the Total Syntheses of Marinoquinolines A and C and Aplidiopsamine A
A Brønsted acid-promoted arene–ynamide
cyclization
has been developed to construct the 3<i>H</i>-pyrroloÂ[2,3-<i>c</i>]Âquinolines. This reaction consists of the generation of
a highly reactive keteniminium intermediate from arene–ynamide
activated by a Brønsted acid and electrophilic aromatic substitution
reaction to give arene-fused quinolines in high yields. This methodology
enabled facile access to marinoquinolines A and C and aplidiopsamine
A
Total Synthesis of (+)-<i>trans</i>-Dihydronarciclasine Utilizing Asymmetric Conjugate Addition
A highly efficient short-step construction of the common phenanthridine skeleton of pancratistatin-class alkaloids was accomplished in enantiomerically pure form using chiral ligand-controlled asymmetric conjugate addition. The utility of the intermediate was demonstrated by the total synthesis of (+)-<i>trans</i>-dihydronarciclasine with mild oxidation from an amine to an amide as a key step
Radical Aminomethylation of Imines
Taking advantage of the high level
of performance of <i>N</i>-alkoxycarbonyl-imines, we achieved
the first example of addition
of the aminomethyl radical to imine. The reaction efficiency depended
on the structure of the radical precursor, whether it is an iodide
or a xanthate, and an electron-withdrawing group on the nitrogen atom
of the radical. This reaction allows direct introduction of an N-substituted
aminomethyl group onto imine to provide 1,2-diamine as well as the
short-step synthesis of ICI-199,441