36 research outputs found
Structure Elucidation and Enantioselective Total Synthesis of the Potent HMG-CoA Reductase Inhibitor FR901512 via Catalytic Asymmetric Nozaki−Hiyama Reactions
Correction to Enantioselective Total Synthesis of (+)-Colletoic Acid via Catalytic Asymmetric Intramolecular Cyclopropanation of an α‑Diazo-β-keto Diphenylphosphine Oxide
Correction to Enantioselective Total Synthesis of (+)-Colletoic Acid via Catalytic Asymmetric Intramolecular Cyclopropanation of an α‑Diazo-β-keto Diphenylphosphine Oxid
A Non-Heme Iron(III) Complex with Porphyrin-like Properties That Catalyzes Asymmetric Epoxidation
In this report, we describe an ironÂ(III) complex containing
a carbazole-based tridentate ligand that catalyzes highly enantioselective
asymmetric epoxidation of (<i>E</i>)-alkenes at room temperature.
The non-heme ironÂ(III) complex has a five-coordinated trigonal-bipyramidal
structure, and its two-electron oxidized state has the similar electronic
structure as that of iron porphyrins
Asymmetric Catalysis of Nozaki−Hiyama Allylation and Methallylation with A New Tridentate Bis(oxazolinyl)carbazole Ligand
Enantioselective Total Synthesis of (+)-Colletoic Acid via Catalytic Asymmetric Intramolecular Cyclopropanation of an α‑Diazo-β-keto Diphenylphosphine Oxide
The enantioselective total synthesis of (+)-colletoic acid, a potent naturally occurring 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) inhibitor, is described. This total synthesis features a highly enantioselective catalytic asymmetric intramolecular cyclopropanation of an α-diazo-β-keto diphenylphosphine oxide and five highly stereoselective reactions (cyclopropane opening, Diels–Alder reaction, iodolactonization, alkene formation, and reduction of α,β-unsaturated carboxylic acid)
Enantioselective Approach to Polycyclic Polyprenylated Acylphloroglucinols via Catalytic Asymmetric Intramolecular Cyclopropanation
The formal enantioselective
total synthesis of nemorosone, garsubellin A, clusianone, and hyperforin
is described. The catalytic asymmetric intramolecular cyclopropanation
(CAIMCP) of an α-diazo ketone, a common synthetic intermediate
for the above four polycyclic polyprenylated acylphloroglucinols previously
reported by us, exhibited low enantioselectivity. However, CAIMCP
of the corresponding α-diazo β-keto sulfone afforded the
desired product in 79% yield with 84% ee. Investigation of the CAIMCP
of the α-diazo β-keto sulfone demonstrated the formation
of a rearrangement product in the presence of molecular sieves 4 Ã…,
whereas, in the presence of H<sub>2</sub>O, the byproduct derived
from ring-opening of the desired cyclopropane was observed. X-ray
crystallographic analysis suggested that the above two products are
derived from the same chiral intermediate. The product derived from
ring-opening of the cyclopropane was successfully transformed to the
respective synthetic intermediates for the total syntheses of nemorosone,
garsubellin A, clusianone, and hyperforin, which had previously been
reported by us
Enantioselective Approach to Polycyclic Polyprenylated Acylphloroglucinols via Catalytic Asymmetric Intramolecular Cyclopropanation
The formal enantioselective
total synthesis of nemorosone, garsubellin A, clusianone, and hyperforin
is described. The catalytic asymmetric intramolecular cyclopropanation
(CAIMCP) of an α-diazo ketone, a common synthetic intermediate
for the above four polycyclic polyprenylated acylphloroglucinols previously
reported by us, exhibited low enantioselectivity. However, CAIMCP
of the corresponding α-diazo β-keto sulfone afforded the
desired product in 79% yield with 84% ee. Investigation of the CAIMCP
of the α-diazo β-keto sulfone demonstrated the formation
of a rearrangement product in the presence of molecular sieves 4 Ã…,
whereas, in the presence of H<sub>2</sub>O, the byproduct derived
from ring-opening of the desired cyclopropane was observed. X-ray
crystallographic analysis suggested that the above two products are
derived from the same chiral intermediate. The product derived from
ring-opening of the cyclopropane was successfully transformed to the
respective synthetic intermediates for the total syntheses of nemorosone,
garsubellin A, clusianone, and hyperforin, which had previously been
reported by us
Correction to Synthetic Studies on Taxol: Highly Stereoselective Construction of the Taxol C‑Ring via S<sub>N</sub>2′ Reduction of an Allylic Phosphonium Salt
Correction to Synthetic Studies on Taxol: Highly Stereoselective
Construction of the Taxol C‑Ring via S<sub>N</sub>2′
Reduction of an Allylic Phosphonium Sal
Stereoselective Total Synthesis of Nemorosone
The highly stereoselective total synthesis of nemorosone
via a new approach to the bicyclo[3.3.1]Ânonane-2,4,9-trione core which
features intramolecular cyclopropanation of an α-diazo ketone,
stereoselective alkylation at the C8 position, and regioselective
ring-opening
of cyclopropane is described. The total synthesis of nemorosone includes
chemo- and stereoselective hydrogenation directed by the internal
alkene
Enantioselective Approach to Polycyclic Polyprenylated Acylphloroglucinols via Catalytic Asymmetric Intramolecular Cyclopropanation
The formal enantioselective
total synthesis of nemorosone, garsubellin A, clusianone, and hyperforin
is described. The catalytic asymmetric intramolecular cyclopropanation
(CAIMCP) of an α-diazo ketone, a common synthetic intermediate
for the above four polycyclic polyprenylated acylphloroglucinols previously
reported by us, exhibited low enantioselectivity. However, CAIMCP
of the corresponding α-diazo β-keto sulfone afforded the
desired product in 79% yield with 84% ee. Investigation of the CAIMCP
of the α-diazo β-keto sulfone demonstrated the formation
of a rearrangement product in the presence of molecular sieves 4 Ã…,
whereas, in the presence of H<sub>2</sub>O, the byproduct derived
from ring-opening of the desired cyclopropane was observed. X-ray
crystallographic analysis suggested that the above two products are
derived from the same chiral intermediate. The product derived from
ring-opening of the cyclopropane was successfully transformed to the
respective synthetic intermediates for the total syntheses of nemorosone,
garsubellin A, clusianone, and hyperforin, which had previously been
reported by us