A new chiral disulfonamide ligand derived from α-amino acid for catalytic enantioselective cyclopropanation
✍ Scribed by Nobuyuki Imai; Katsumasa Sakamoto; Masahiro Maeda; Kazushi Kouge; Kenji Yoshizane; Junzo Nokami
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- French
- Weight
- 216 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0040-4039
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## Abstract Chiral ligands derived from L‐proline are found to catalyze the Simmons—Smith cyclopropanation of cinnamyl alcohol (I).
The easily prepared chiral tertiary amino alcohol 1a was found to catalyze the reaction of alkynylzinc reagents with various aldehydes to generate chiral propargylic alcohols with moderate-to-good enantioselectivities. The mechanism of the reaction is also discussed in this Letter. A novel theoretic
## Abstract An enantioselective Michael addition of ethyl 4,4,4‐trifluoro‐3‐oxobutanoate to __α__,__β__‐unsaturated ketone esters using a chiral alkyl‐substituted thiourea catalyst is reported. Excellent levels of stereo‐induction (up to 98% __ee__) under mild reaction conditions were obtained to a