Isao Takahashi

Structural Elucidation of YM-75518, A Novel Antifungal Antibiotic Isolated from Pseudomonas sp. Q38009

An antifungal antibiotic, YM-75518, was isolated from the fermentation broth of Pseudomonas sp. Q38009. Structural elucidation of YM-75518 was accomplished through extensive 2D NMR spectroscopy including 15N-1H HMQC and 15N-HMBC at natural abundance. YM-75518 consisted of a unique 15-membered macrolactone ring and a methoxy imino structure.

Asymmetric Synthesis of Atropisomeric Compounds with an N‒C Chiral Axis

Introduction .....................................................................................2 I. Diastereoselective Synthesis using Chiral Pool Precursors .................4 1. Synthesis of Axially Chiral Anilides from (S)-Lactic Acid Derivatives......... 4 2. Synthesis of Axially Chiral Lactams from (S)-5-Hydroxymethylbutyrolactone and (l)-Menthol .................................. 5 3. Synthesis of Axially Chiral Indoles and Acridanes from Planar Chiral Cr-Arene Compounds .............................................................................. 6 II. Enantioselective Synthesis using Stoichiometric Chiral Reagent ........8 1. Synthesis of Axially Chiral Anilides and Lactams through Kinetic Resolution using a Chiral Base ................................................................ 8 2. Synthesis of Axially Chiral Anilides and Imides through Enantioselective Deprotonation using a Chiral Base ................................. 8 III. Catalytic Asymmetric Synthesis of N C Axially Chiral Compounds ......................................................................... 10 1. Synthesis through Catalytic Enantioselective N C Bond Formation .........10 2. Synthesis through Catalytic Enantioselective [2+2+2] Cycloaddition........15 3. Synthesis through Catalytic Enantioselective 1,4-Addition ........................16 4. Synthesis through Catalytic Enantioselective Protonation.........................17 5. Synthesis through Catalytic Enantioselective Oxidation............................17 6. Synthesis through Catalytic Enantioselective Friedel-Crafts Reaction .......18 Acknowledgment ............................................................................ 19 References ...................................................................................... 19

Catalytic Enantioselective Synthesis of N-C Axially Chiral Phenanthridin-6-one Derivatives.

N-C axially chiral phenanthridin-6-one derivatives bearing various ortho-substituted phenyl groups on the nitrogen atom were enantioselectively prepared through (R)-DTBM-SEGPHOS-Pd(OAc)2-catalyzed intramolecular Buchwald-Hartwig amination. The enantioselectivity strongly depended on solvents, bases, and reaction temperature as well as on the bulkiness of ortho-substituents.